♻️ Break down the graph and solver

lib/calculator.dart

@@ -1,5 +1,6 @@
 // === 在 abstract class Expr 中添加声明 ===
-import 'dart:math' show sqrt, cos, sin, tan;
+import 'dart:math' show sqrt, cos, sin, tan, pow, log, exp, asin, acos, atan;
+import 'parser.dart';
 
 abstract class Expr {
   Expr simplify();
@@ -7,6 +8,9 @@ abstract class Expr {
   /// 新增：对表达式进行“求值/数值化”——尽可能把可算的部分算出来
   Expr evaluate();
 
+  /// Substitute variable with value
+  Expr substitute(String varName, Expr value);
+
   @override
   String toString();
 
@@ -27,6 +31,9 @@ class IntExpr extends Expr {
   @override
   Expr evaluate() => this;
 
+  @override
+  Expr substitute(String varName, Expr value) => this;
+
   @override
   String toString() => value.toString();
 }
@@ -42,10 +49,31 @@ class DoubleExpr extends Expr {
   @override
   Expr evaluate() => this;
 
+  @override
+  Expr substitute(String varName, Expr value) => this;
+
   @override
   String toString() => value.toString();
 }
 
+// === VarExpr ===
+class VarExpr extends Expr {
+  final String name;
+  VarExpr(this.name);
+
+  @override
+  Expr simplify() => this;
+
+  @override
+  Expr evaluate() => this;
+
+  @override
+  Expr substitute(String varName, Expr value) => name == varName ? value : this;
+
+  @override
+  String toString() => name;
+}
+
 // === FractionExpr.evaluate ===
 class FractionExpr extends Expr {
   final int numerator;
@@ -74,6 +102,9 @@ class FractionExpr extends Expr {
   @override
   Expr evaluate() => simplify();
 
+  @override
+  Expr substitute(String varName, Expr value) => this;
+
   @override
   String toString() => "$numerator/$denominator";
 }
@@ -150,6 +181,12 @@ class AddExpr extends Expr {
     return AddExpr(l, r);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) => AddExpr(
+    left.substitute(varName, value),
+    right.substitute(varName, value),
+  );
+
   @override
   String toString() => "($left + $right)";
 }
@@ -213,6 +250,12 @@ class SubExpr extends Expr {
     return SubExpr(l, r);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) => SubExpr(
+    left.substitute(varName, value),
+    right.substitute(varName, value),
+  );
+
   @override
   String toString() => "($left - $right)";
 }
@@ -296,6 +339,12 @@ class MulExpr extends Expr {
     return MulExpr(l, r);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) => MulExpr(
+    left.substitute(varName, value),
+    right.substitute(varName, value),
+  );
+
   @override
   String toString() => "($left * $right)";
 }
@@ -378,6 +427,12 @@ class DivExpr extends Expr {
     return DivExpr(l, r);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) => DivExpr(
+    left.substitute(varName, value),
+    right.substitute(varName, value),
+  );
+
   @override
   String toString() => "($left / $right)";
 }
@@ -430,7 +485,11 @@ class SqrtExpr extends Expr {
   }
 
   @override
-  String toString() => "sqrt($inner)";
+  Expr substitute(String varName, Expr value) =>
+      SqrtExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "\\sqrt{${inner.toString()}}";
 }
 
 // === CosExpr ===
@@ -456,6 +515,10 @@ class CosExpr extends Expr {
     return CosExpr(i);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) =>
+      CosExpr(inner.substitute(varName, value));
+
   @override
   String toString() => "cos($inner)";
 }
@@ -483,6 +546,10 @@ class SinExpr extends Expr {
     return SinExpr(i);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) =>
+      SinExpr(inner.substitute(varName, value));
+
   @override
   String toString() => "sin($inner)";
 }
@@ -510,10 +577,285 @@ class TanExpr extends Expr {
     return TanExpr(i);
   }
 
+  @override
+  Expr substitute(String varName, Expr value) =>
+      TanExpr(inner.substitute(varName, value));
+
   @override
   String toString() => "tan($inner)";
 }
 
+// === PowExpr ===
+class PowExpr extends Expr {
+  final Expr left, right;
+  PowExpr(this.left, this.right);
+
+  @override
+  Expr simplify() {
+    var l = left.simplify();
+    var r = right.simplify();
+
+    // x^0 = 1
+    if (r is IntExpr && r.value == 0) return IntExpr(1);
+    // x^1 = x
+    if (r is IntExpr && r.value == 1) return l;
+    // 1^x = 1
+    if (l is IntExpr && l.value == 1) return IntExpr(1);
+    // 0^x = 0 (for x != 0)
+    if (l is IntExpr && l.value == 0 && !(r is IntExpr && r.value == 0)) {
+      return IntExpr(0);
+    }
+
+    return PowExpr(l, r);
+  }
+
+  @override
+  Expr evaluate() {
+    var l = left.evaluate();
+    var r = right.evaluate();
+
+    // x^0 = 1
+    if (r is IntExpr && r.value == 0) return IntExpr(1);
+    // x^1 = x
+    if (r is IntExpr && r.value == 1) return l;
+    // 1^x = 1
+    if (l is IntExpr && l.value == 1) return IntExpr(1);
+    // 0^x = 0 (for x != 0)
+    if (l is IntExpr && l.value == 0 && !(r is IntExpr && r.value == 0)) {
+      return IntExpr(0);
+    }
+
+    // If both are numbers, compute
+    if (l is IntExpr && r is IntExpr) {
+      return DoubleExpr(pow(l.value.toDouble(), r.value.toDouble()).toDouble());
+    }
+    if (l is DoubleExpr && r is IntExpr) {
+      return DoubleExpr(pow(l.value, r.value.toDouble()).toDouble());
+    }
+    if (l is IntExpr && r is DoubleExpr) {
+      return DoubleExpr(pow(l.value.toDouble(), r.value).toDouble());
+    }
+    if (l is DoubleExpr && r is DoubleExpr) {
+      return DoubleExpr(pow(l.value, r.value).toDouble());
+    }
+
+    return PowExpr(l, r);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) => PowExpr(
+    left.substitute(varName, value),
+    right.substitute(varName, value),
+  );
+
+  @override
+  String toString() {
+    String leftStr = left.toString();
+    String rightStr = right.toString();
+
+    // Remove outer parentheses
+    if (leftStr.startsWith('(') && leftStr.endsWith(')')) {
+      leftStr = leftStr.substring(1, leftStr.length - 1);
+    }
+    if (rightStr.startsWith('(') && rightStr.endsWith(')')) {
+      rightStr = rightStr.substring(1, rightStr.length - 1);
+    }
+
+    // Add parentheses around base if it's a complex expression
+    bool needsParens =
+        !(left is VarExpr || left is IntExpr || left is DoubleExpr);
+    String base = needsParens ? '($leftStr)' : leftStr;
+
+    return '$base^{$rightStr}';
+  }
+}
+
+// === LogExpr ===
+class LogExpr extends Expr {
+  final Expr inner;
+  LogExpr(this.inner);
+
+  @override
+  Expr simplify() => LogExpr(inner.simplify());
+
+  @override
+  Expr evaluate() {
+    var i = inner.evaluate();
+    if (i is IntExpr) {
+      return DoubleExpr(log(i.value.toDouble()));
+    }
+    if (i is FractionExpr) {
+      return DoubleExpr(log(i.numerator / i.denominator));
+    }
+    if (i is DoubleExpr) {
+      return DoubleExpr(log(i.value));
+    }
+    return LogExpr(i);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) =>
+      LogExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "log($inner)";
+}
+
+// === ExpExpr ===
+class ExpExpr extends Expr {
+  final Expr inner;
+  ExpExpr(this.inner);
+
+  @override
+  Expr simplify() => ExpExpr(inner.simplify());
+
+  @override
+  Expr evaluate() {
+    var i = inner.evaluate();
+    if (i is IntExpr) {
+      return DoubleExpr(exp(i.value.toDouble()));
+    }
+    if (i is FractionExpr) {
+      return DoubleExpr(exp(i.numerator / i.denominator));
+    }
+    if (i is DoubleExpr) {
+      return DoubleExpr(exp(i.value));
+    }
+    return ExpExpr(i);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) =>
+      ExpExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "exp($inner)";
+}
+
+// === AsinExpr ===
+class AsinExpr extends Expr {
+  final Expr inner;
+  AsinExpr(this.inner);
+
+  @override
+  Expr simplify() => AsinExpr(inner.simplify());
+
+  @override
+  Expr evaluate() {
+    var i = inner.evaluate();
+    if (i is IntExpr) {
+      return DoubleExpr(asin(i.value.toDouble()));
+    }
+    if (i is FractionExpr) {
+      return DoubleExpr(asin(i.numerator / i.denominator));
+    }
+    if (i is DoubleExpr) {
+      return DoubleExpr(asin(i.value));
+    }
+    return AsinExpr(i);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) =>
+      AsinExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "asin($inner)";
+}
+
+// === AcosExpr ===
+class AcosExpr extends Expr {
+  final Expr inner;
+  AcosExpr(this.inner);
+
+  @override
+  Expr simplify() => AcosExpr(inner.simplify());
+
+  @override
+  Expr evaluate() {
+    var i = inner.evaluate();
+    if (i is IntExpr) {
+      return DoubleExpr(acos(i.value.toDouble()));
+    }
+    if (i is FractionExpr) {
+      return DoubleExpr(acos(i.numerator / i.denominator));
+    }
+    if (i is DoubleExpr) {
+      return DoubleExpr(acos(i.value));
+    }
+    return AcosExpr(i);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) =>
+      AcosExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "acos($inner)";
+}
+
+// === AtanExpr ===
+class AtanExpr extends Expr {
+  final Expr inner;
+  AtanExpr(this.inner);
+
+  @override
+  Expr simplify() => AtanExpr(inner.simplify());
+
+  @override
+  Expr evaluate() {
+    var i = inner.evaluate();
+    if (i is IntExpr) {
+      return DoubleExpr(atan(i.value.toDouble()));
+    }
+    if (i is FractionExpr) {
+      return DoubleExpr(atan(i.numerator / i.denominator));
+    }
+    if (i is DoubleExpr) {
+      return DoubleExpr(atan(i.value));
+    }
+    return AtanExpr(i);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) =>
+      AtanExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "atan($inner)";
+}
+
+// === AbsExpr ===
+class AbsExpr extends Expr {
+  final Expr inner;
+  AbsExpr(this.inner);
+
+  @override
+  Expr simplify() => AbsExpr(inner.simplify());
+
+  @override
+  Expr evaluate() {
+    var i = inner.evaluate();
+    if (i is IntExpr) {
+      return IntExpr(i.value.abs());
+    }
+    if (i is FractionExpr) {
+      return FractionExpr(i.numerator.abs(), i.denominator);
+    }
+    if (i is DoubleExpr) {
+      return DoubleExpr(i.value.abs());
+    }
+    return AbsExpr(i);
+  }
+
+  @override
+  Expr substitute(String varName, Expr value) =>
+      AbsExpr(inner.substitute(varName, value));
+
+  @override
+  String toString() => "|$inner|";
+}
+
 // === 辅助：识别 a * sqrt(X) 形式 ===
 class _SqrtTerm {
   final int coef;
@@ -535,5 +877,159 @@ _SqrtTerm? _asSqrtTerm(Expr e) {
   return null;
 }
 
+/// 获取精确三角函数结果
+String? getExactTrigResult(String input) {
+  final cleanInput = input.replaceAll(' ', '').toLowerCase();
+
+  // 匹配 sin(角度) 模式
+  final sinMatch = RegExp(r'^sin\((\d+(?:\+\d+)*)\)$').firstMatch(cleanInput);
+  if (sinMatch != null) {
+    final angleExpr = sinMatch.group(1)!;
+    final angle = evaluateAngleExpression(angleExpr);
+    if (angle != null) {
+      return getSinExactValue(angle);
+    }
+  }
+
+  // 匹配 cos(角度) 模式
+  final cosMatch = RegExp(r'^cos\((\d+(?:\+\d+)*)\)$').firstMatch(cleanInput);
+  if (cosMatch != null) {
+    final angleExpr = cosMatch.group(1)!;
+    final angle = evaluateAngleExpression(angleExpr);
+    if (angle != null) {
+      return getCosExactValue(angle);
+    }
+  }
+
+  // 匹配 tan(角度) 模式
+  final tanMatch = RegExp(r'^tan\((\d+(?:\+\d+)*)\)$').firstMatch(cleanInput);
+  if (tanMatch != null) {
+    final angleExpr = tanMatch.group(1)!;
+    final angle = evaluateAngleExpression(angleExpr);
+    if (angle != null) {
+      return getTanExactValue(angle);
+    }
+  }
+
+  return null;
+}
+
+/// 获取 sin 的精确值
+String? getSinExactValue(int angle) {
+  // 标准化角度到 0-360 度
+  final normalizedAngle = angle % 360;
+
+  switch (normalizedAngle) {
+    case 0:
+    case 360:
+      return '0';
+    case 30:
+      return '\\frac{1}{2}';
+    case 45:
+      return '\\frac{\\sqrt{2}}{2}';
+    case 60:
+      return '\\frac{\\sqrt{3}}{2}';
+    case 75:
+      return '1 + \\frac{\\sqrt{2}}{2}';
+    case 90:
+      return '1';
+    case 120:
+      return '\\frac{\\sqrt{3}}{2}';
+    case 135:
+      return '\\frac{\\sqrt{2}}{2}';
+    case 150:
+      return '\\frac{1}{2}';
+    case 180:
+      return '0';
+    case 210:
+      return '-\\frac{1}{2}';
+    case 225:
+      return '-\\frac{\\sqrt{2}}{2}';
+    case 240:
+      return '-\\frac{\\sqrt{3}}{2}';
+    case 270:
+      return '-1';
+    case 300:
+      return '-\\frac{\\sqrt{3}}{2}';
+    case 315:
+      return '-\\frac{\\sqrt{2}}{2}';
+    case 330:
+      return '-\\frac{1}{2}';
+    default:
+      return null;
+  }
+}
+
+/// 获取 cos 的精确值
+String? getCosExactValue(int angle) {
+  // cos(angle) = sin(90 - angle)
+  final complementaryAngle = 90 - angle;
+  return getSinExactValue(complementaryAngle.abs());
+}
+
+/// 获取 tan 的精确值
+String? getTanExactValue(int angle) {
+  // tan(angle) = sin(angle) / cos(angle)
+  final sinValue = getSinExactValue(angle);
+  final cosValue = getCosExactValue(angle);
+
+  if (sinValue != null && cosValue != null) {
+    if (cosValue == '0') return null; // 未定义
+    return '\\frac{$sinValue}{$cosValue}';
+  }
+
+  return null;
+}
+
+/// 将数值结果格式化为几倍根号的形式
+String formatSqrtResult(double result) {
+  // 处理负数
+  if (result < 0) {
+    return '-${formatSqrtResult(-result)}';
+  }
+
+  // 处理零
+  if (result == 0) return '0';
+
+  // 检查是否接近整数
+  final rounded = result.round();
+  if ((result - rounded).abs() < 1e-10) {
+    return rounded.toString();
+  }
+
+  // 计算 result 的平方，看它是否接近整数
+  final squared = result * result;
+  final squaredRounded = squared.round();
+
+  // 如果 squared 接近整数，说明 result 是某个数的平方根
+  if ((squared - squaredRounded).abs() < 1e-6) {
+    // 寻找最大的完全平方数因子
+    int maxSquareFactor = 1;
+    for (int i = 2; i * i <= squaredRounded; i++) {
+      if (squaredRounded % (i * i) == 0) {
+        maxSquareFactor = i * i;
+      }
+    }
+
+    final coefficient = sqrt(maxSquareFactor).round();
+    final remaining = squaredRounded ~/ maxSquareFactor;
+
+    if (remaining == 1) {
+      // 完全平方数，直接返回系数
+      return coefficient.toString();
+    } else if (coefficient == 1) {
+      return '\\sqrt{$remaining}';
+    } else {
+      return '$coefficient\\sqrt{$remaining}';
+    }
+  }
+
+  // 如果不是平方根的结果，返回原始数值（保留几位小数）
+  return result
+      .toStringAsFixed(6)
+      .replaceAll(RegExp(r'\.0+$'), '')
+      .replaceAll(RegExp(r'\.$'), '');
+}
+
 /// 辗转相除法求 gcd
 int _gcd(int a, int b) => b == 0 ? a : _gcd(b, a % b);

lib/parser.dart

@@ -33,12 +33,12 @@ class Parser {
   }
 
   Expr parseMul() {
-    var expr = parseAtom();
+    var expr = parsePow();
     skipSpaces();
     while (!isEnd && (current == '*' || current == '/')) {
       var op = current;
       eat();
-      var right = parseAtom();
+      var right = parsePow();
       if (op == '*') {
         expr = MulExpr(expr, right);
       } else {
@@ -49,63 +49,171 @@ class Parser {
     return expr;
   }
 
-  Expr parseAtom() {
+  Expr parsePow() {
+    var expr = parseAtom();
     skipSpaces();
-    if (current == '(') {
+    if (!isEnd && current == '^') {
-      eat();
-      var expr = parse();
-      if (current != ')') throw Exception("缺少 )");
       eat();
+      var right = parsePow(); // right associative
+      return PowExpr(expr, right);
+    }
     return expr;
   }
 
-    if (input.startsWith("sqrt", pos)) {
+  Expr parseAtom() {
+    skipSpaces();
+    bool negative = false;
+    if (current == '-') {
+      negative = true;
+      eat();
+      skipSpaces();
+    }
+    Expr expr;
+    if (current == '(') {
+      eat();
+      expr = parse();
+      if (current != ')') throw Exception("缺少 )");
+      eat();
+    } else if (input.startsWith("sqrt", pos)) {
       pos += 4;
       if (current != '(') throw Exception("sqrt 缺少 (");
       eat();
       var inner = parse();
       if (current != ')') throw Exception("sqrt 缺少 )");
       eat();
-      return SqrtExpr(inner);
+      expr = SqrtExpr(inner);
-    }
+    } else if (input.startsWith("cos", pos)) {
-
-    if (input.startsWith("cos", pos)) {
       pos += 3;
       if (current != '(') throw Exception("cos 缺少 (");
       eat();
       var inner = parse();
       if (current != ')') throw Exception("cos 缺少 )");
       eat();
-      return CosExpr(inner);
+      expr = CosExpr(inner);
-    }
+    } else if (input.startsWith("sin", pos)) {
-
-    if (input.startsWith("sin", pos)) {
       pos += 3;
       if (current != '(') throw Exception("sin 缺少 (");
       eat();
       var inner = parse();
       if (current != ')') throw Exception("sin 缺少 )");
       eat();
-      return SinExpr(inner);
+      expr = SinExpr(inner);
-    }
+    } else if (input.startsWith("tan", pos)) {
-
-    if (input.startsWith("tan", pos)) {
       pos += 3;
       if (current != '(') throw Exception("tan 缺少 (");
       eat();
       var inner = parse();
       if (current != ')') throw Exception("tan 缺少 )");
       eat();
-      return TanExpr(inner);
+      expr = TanExpr(inner);
-    }
+    } else if (input.startsWith("log", pos)) {
-
+      pos += 3;
-    // 解析整数
+      if (current != '(') throw Exception("log 缺少 (");
+      eat();
+      var inner = parse();
+      if (current != ')') throw Exception("log 缺少 )");
+      eat();
+      expr = LogExpr(inner);
+    } else if (input.startsWith("exp", pos)) {
+      pos += 3;
+      if (current != '(') throw Exception("exp 缺少 (");
+      eat();
+      var inner = parse();
+      if (current != ')') throw Exception("exp 缺少 )");
+      eat();
+      expr = ExpExpr(inner);
+    } else if (input.startsWith("asin", pos)) {
+      pos += 4;
+      if (current != '(') throw Exception("asin 缺少 (");
+      eat();
+      var inner = parse();
+      if (current != ')') throw Exception("asin 缺少 )");
+      eat();
+      expr = AsinExpr(inner);
+    } else if (input.startsWith("acos", pos)) {
+      pos += 4;
+      if (current != '(') throw Exception("acos 缺少 (");
+      eat();
+      var inner = parse();
+      if (current != ')') throw Exception("acos 缺少 )");
+      eat();
+      expr = AcosExpr(inner);
+    } else if (input.startsWith("atan", pos)) {
+      pos += 4;
+      if (current != '(') throw Exception("atan 缺少 (");
+      eat();
+      var inner = parse();
+      if (current != ')') throw Exception("atan 缺少 )");
+      eat();
+      expr = AtanExpr(inner);
+    } else if (current == '|') {
+      eat();
+      var inner = parse();
+      if (current != '|') throw Exception("abs 缺少 |");
+      eat();
+      expr = AbsExpr(inner);
+    } else if (RegExp(r'[a-zA-Z]').hasMatch(current)) {
+      var varName = current;
+      eat();
+      expr = VarExpr(varName);
+    } else {
+      // 解析数字 (整数或小数)
       var buf = '';
-    while (!isEnd && RegExp(r'\d').hasMatch(current)) {
+      bool hasDot = false;
+      while (!isEnd &&
+          (RegExp(r'\d').hasMatch(current) || (!hasDot && current == '.'))) {
+        if (current == '.') hasDot = true;
         buf += current;
         eat();
       }
       if (buf.isEmpty) throw Exception("无法解析: $current");
-    return IntExpr(int.parse(buf));
+      if (hasDot) {
+        expr = DoubleExpr(double.parse(buf));
+      } else {
+        expr = IntExpr(int.parse(buf));
+      }
+    }
+    if (negative) {
+      expr = SubExpr(IntExpr(0), expr);
+    }
+    return expr;
   }
 }
+
+/// 计算角度表达式（如 30+45 = 75）
+int? evaluateAngleExpression(String expr) {
+  final parts = expr.split('+');
+  int sum = 0;
+  for (final part in parts) {
+    final num = int.tryParse(part.trim());
+    if (num == null) return null;
+    sum += num;
+  }
+  return sum;
+}
+
+/// 将三角函数的参数从度转换为弧度
+String convertTrigToRadians(String input) {
+  String result = input;
+
+  // 正则表达式匹配三角函数调用，如 sin(30), cos(45), tan(60)
+  final trigPattern = RegExp(
+    r'(sin|cos|tan|asin|acos|atan)\s*\(\s*([^)]+)\s*\)',
+    caseSensitive: false,
+  );
+
+  result = result.replaceAllMapped(trigPattern, (match) {
+    final func = match.group(1)!;
+    final arg = match.group(2)!;
+
+    // 如果参数已经是弧度相关的表达式（包含 pi 或 π），则不转换
+    if (arg.contains('pi') || arg.contains('π') || arg.contains('rad')) {
+      return '$func($arg)';
+    }
+
+    // 将度数转换为弧度：度 * π / 180
+    return '$func(($arg)*(π/180))';
+  });
+
+  return result;
+}

lib/screens/calculator_home_page.dart

@@ -2,8 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:latext/latext.dart';
 import 'package:simple_math_calc/models/calculation_step.dart';
 import 'package:simple_math_calc/solver.dart';
-import 'package:fl_chart/fl_chart.dart';
+import 'package:simple_math_calc/widgets/graph_card.dart';
-import 'package:math_expressions/math_expressions.dart' as math_expressions;
 import 'dart:math';
 
 class CalculatorHomePage extends StatefulWidget {
@@ -20,6 +19,7 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
 
   CalculationResult? _result;
   bool _isLoading = false;
+  bool _isFunctionMode = false;
   double _zoomFactor = 1.0;
 
   @override
@@ -40,126 +40,23 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
     setState(() {});
   }
 
-  /// 生成函数图表的点
-  List<FlSpot> _generatePlotPoints(String expression, double zoomFactor) {
-    try {
-      // 如果是方程，取左边作为函数
-      String functionExpr = expression;
-      if (expression.contains('=')) {
-        functionExpr = expression.split('=')[0].trim();
-      }
-
-      // 如果表达式不包含 x，返回空列表
-      if (!functionExpr.contains('x') && !functionExpr.contains('X')) {
-        return [];
-      }
-
-      // 预处理表达式，确保格式正确
-      functionExpr = functionExpr.replaceAll(' ', '');
-
-      // 在数字和变量之间插入乘号
-      functionExpr = functionExpr.replaceAllMapped(
-        RegExp(r'(\d)([a-zA-Z])'),
-        (match) => '${match.group(1)}*${match.group(2)}',
-      );
-
-      // 在变量和数字之间插入乘号 (如 x2 -> x*2)
-      functionExpr = functionExpr.replaceAllMapped(
-        RegExp(r'([a-zA-Z])(\d)'),
-        (match) => '${match.group(1)}*${match.group(2)}',
-      );
-
-      // 解析表达式
-      final parser = math_expressions.ShuntingYardParser();
-      final expr = parser.parse(functionExpr);
-
-      // 创建变量 x
-      final x = math_expressions.Variable('x');
-
-      // 根据缩放因子动态调整范围和步长
-      final range = 10.0 * zoomFactor;
-      final step = max(0.05, 0.2 / zoomFactor); // 缩放时步长更小，放大时步长更大
-
-      // 生成点
-      List<FlSpot> points = [];
-      for (double i = -range; i <= range; i += step) {
-        try {
-          final context = math_expressions.ContextModel()
-            ..bindVariable(x, math_expressions.Number(i));
-          final evaluator = math_expressions.RealEvaluator(context);
-          final y = evaluator.evaluate(expr);
-
-          if (y.isFinite && !y.isNaN) {
-            points.add(FlSpot(i, y.toDouble()));
-          }
-        } catch (e) {
-          // 跳过无法计算的点
-          continue;
-        }
-      }
-
-      // 如果没有足够的点，返回空列表
-      if (points.length < 2) {
-        debugPrint('Generated ${points.length} dots');
-        return [];
-      }
-
-      // 排序点按 x 值
-      points.sort((a, b) => a.x.compareTo(b.x));
-
-      debugPrint(
-        'Generated ${points.length} dots with zoom factor $zoomFactor',
-      );
-      return points;
-    } catch (e) {
-      debugPrint('Error generating plot points: $e');
-      return [];
-    }
-  }
-
-  /// 计算图表的数据范围
-  ({double minX, double maxX, double minY, double maxY}) _calculateChartBounds(
-    List<FlSpot> points,
-    double zoomFactor,
-  ) {
-    if (points.isEmpty) {
-      return (
-        minX: -10 * zoomFactor,
-        maxX: 10 * zoomFactor,
-        minY: -50 * zoomFactor,
-        maxY: 50 * zoomFactor,
-      );
-    }
-
-    double minX = points.first.x;
-    double maxX = points.first.x;
-    double minY = points.first.y;
-    double maxY = points.first.y;
-
-    for (final point in points) {
-      minX = min(minX, point.x);
-      maxX = max(maxX, point.x);
-      minY = min(minY, point.y);
-      maxY = max(maxY, point.y);
-    }
-
-    // 添加边距
-    final xPadding = (maxX - minX) * 0.1;
-    final yPadding = (maxY - minY) * 0.1;
-
-    return (
-      minX: minX - xPadding,
-      maxX: maxX + xPadding,
-      minY: minY - yPadding,
-      maxY: maxY + yPadding,
-    );
-  }
-
   void _solveEquation() {
     if (_controller.text.isEmpty) {
       return;
     }
+
+    final input = _controller.text.trim();
+    final normalizedInput = input.replaceAll(' ', '');
+    if (normalizedInput.toLowerCase().startsWith('y=')) {
       setState(() {
+        _isFunctionMode = true;
+        _result = null;
+      });
+      return;
+    }
+
+    setState(() {
+      _isFunctionMode = false;
       _isLoading = true;
       _result = null; // 清除上次结果
     });
@@ -240,6 +137,13 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
           Expanded(
             child: _isLoading
                 ? const Center(child: CircularProgressIndicator())
+                : _isFunctionMode
+                ? GraphCard(
+                    expression: _controller.text,
+                    zoomFactor: _zoomFactor,
+                    onZoomIn: _zoomIn,
+                    onZoomOut: _zoomOut,
+                  )
                 : _result == null
                 ? const Center(child: Text('请输入方程开始计算'))
                 : buildResultView(_result!),
@@ -354,106 +258,6 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
             ),
           ),
         ),
-        const SizedBox(height: 16),
-        Card(
-          child: Padding(
-            padding: const EdgeInsets.all(16.0),
-            child: Column(
-              children: [
-                Row(
-                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
-                  children: [
-                    Padding(
-                      padding: const EdgeInsets.only(left: 4),
-                      child: Text(
-                        '函数图像',
-                        style: Theme.of(context).textTheme.titleMedium,
-                      ),
-                    ),
-                    Row(
-                      mainAxisAlignment: MainAxisAlignment.center,
-                      children: [
-                        IconButton(
-                          onPressed: _zoomIn,
-                          icon: Icon(Icons.zoom_in),
-                          tooltip: '放大',
-                          padding: EdgeInsets.zero,
-                          visualDensity: VisualDensity.compact,
-                        ),
-                        IconButton(
-                          onPressed: _zoomOut,
-                          icon: Icon(Icons.zoom_out),
-                          tooltip: '缩小',
-                          padding: EdgeInsets.zero,
-                          visualDensity: VisualDensity.compact,
-                        ),
-                      ],
-                    ),
-                  ],
-                ),
-                const SizedBox(height: 24),
-                SizedBox(
-                  height: 340,
-                  child: Builder(
-                    builder: (context) {
-                      final points = _generatePlotPoints(
-                        _controller.text,
-                        _zoomFactor,
-                      );
-                      final bounds = _calculateChartBounds(points, _zoomFactor);
-
-                      return LineChart(
-                        LineChartData(
-                          gridData: FlGridData(show: true),
-                          titlesData: FlTitlesData(
-                            leftTitles: AxisTitles(
-                              sideTitles: SideTitles(
-                                showTitles: true,
-                                reservedSize: 40,
-                              ),
-                            ),
-                            bottomTitles: AxisTitles(
-                              sideTitles: SideTitles(
-                                showTitles: true,
-                                reservedSize: 30,
-                              ),
-                            ),
-                            topTitles: AxisTitles(
-                              sideTitles: SideTitles(showTitles: false),
-                            ),
-                            rightTitles: AxisTitles(
-                              sideTitles: SideTitles(showTitles: false),
-                            ),
-                          ),
-                          borderData: FlBorderData(
-                            show: true,
-                            border: Border.all(
-                              color: Theme.of(context).colorScheme.outline,
-                            ),
-                          ),
-                          lineBarsData: [
-                            LineChartBarData(
-                              spots: points,
-                              isCurved: true,
-                              color: Theme.of(context).colorScheme.primary,
-                              barWidth: 3,
-                              belowBarData: BarAreaData(show: false),
-                              dotData: FlDotData(show: false),
-                            ),
-                          ],
-                          minX: bounds.minX,
-                          maxX: bounds.maxX,
-                          minY: bounds.minY,
-                          maxY: bounds.maxY,
-                        ),
-                      );
-                    },
-                  ),
-                ),
-              ],
-            ),
-          ),
-        ),
       ],
     );
   }

lib/solver.dart

@@ -1,4 +1,5 @@
 import 'dart:math';
+import 'package:flutter/foundation.dart';
 import 'package:rational/rational.dart';
 import 'models/calculation_step.dart';
 import 'calculator.dart';
@@ -52,17 +53,22 @@ class SolverService {
   /// 1. 求解简单表达式
   CalculationResult _solveSimpleExpression(String input) {
     final steps = <CalculationStep>[];
+    // Parse the input to get LaTeX-formatted version
+    final parser = Parser(input);
+    final parsedExpr = parser.parse();
+    final latexInput = parsedExpr.toString().replaceAll('*', '\\cdot');
+
     steps.add(
       CalculationStep(
         stepNumber: 1,
         title: '表达式求值',
         explanation: '这是一个标准的数学表达式，我们将直接计算其结果。',
-        formula: '\$\$$input\$\$',
+        formula: '\$\$$latexInput\$\$',
       ),
     );
 
     // 检查是否为特殊三角函数值，可以返回精确结果
-    final exactTrigResult = _getExactTrigResult(input);
+    final exactTrigResult = getExactTrigResult(input);
     if (exactTrigResult != null) {
       return CalculationResult(
         steps: steps,
@@ -71,7 +77,7 @@ class SolverService {
     }
 
     // 预处理输入，将三角函数的参数从度转换为弧度
-    String processedInput = _convertTrigToRadians(input);
+    String processedInput = convertTrigToRadians(input);
 
     try {
       // 使用自定义解析器解析表达式
@@ -99,7 +105,7 @@ class SolverService {
       }
 
       // 尝试将结果格式化为几倍根号的形式
-      final formattedResult = _formatSqrtResult(result);
+      final formattedResult = formatSqrtResult(result);
 
       return CalculationResult(
         steps: steps,
@@ -113,12 +119,17 @@ class SolverService {
   /// 2. 求解一元一次方程
   CalculationResult _solveLinearEquation(String input) {
     final steps = <CalculationStep>[];
+    // Parse the input to get LaTeX-formatted version
+    final parser = Parser(input);
+    final parsedExpr = parser.parse();
+    final latexInput = parsedExpr.toString().replaceAll('*', '\\cdot');
+
     steps.add(
       CalculationStep(
         stepNumber: 0,
         title: '原方程',
         explanation: '这是一元一次方程。',
-        formula: '\$\$$input\$\$',
+        formula: '\$\$$latexInput\$\$',
       ),
     );
 
@@ -503,198 +514,6 @@ ${b1}y &= ${c1 - a1 * x.toDouble()}
 
   /// ---- 辅助函数 ----
 
-  /// 获取精确三角函数结果
-  String? _getExactTrigResult(String input) {
-    final cleanInput = input.replaceAll(' ', '').toLowerCase();
-
-    // 匹配 sin(角度) 模式
-    final sinMatch = RegExp(r'^sin\((\d+(?:\+\d+)*)\)$').firstMatch(cleanInput);
-    if (sinMatch != null) {
-      final angleExpr = sinMatch.group(1)!;
-      final angle = _evaluateAngleExpression(angleExpr);
-      if (angle != null) {
-        return _getSinExactValue(angle);
-      }
-    }
-
-    // 匹配 cos(角度) 模式
-    final cosMatch = RegExp(r'^cos\((\d+(?:\+\d+)*)\)$').firstMatch(cleanInput);
-    if (cosMatch != null) {
-      final angleExpr = cosMatch.group(1)!;
-      final angle = _evaluateAngleExpression(angleExpr);
-      if (angle != null) {
-        return _getCosExactValue(angle);
-      }
-    }
-
-    // 匹配 tan(角度) 模式
-    final tanMatch = RegExp(r'^tan\((\d+(?:\+\d+)*)\)$').firstMatch(cleanInput);
-    if (tanMatch != null) {
-      final angleExpr = tanMatch.group(1)!;
-      final angle = _evaluateAngleExpression(angleExpr);
-      if (angle != null) {
-        return _getTanExactValue(angle);
-      }
-    }
-
-    return null;
-  }
-
-  /// 计算角度表达式（如 30+45 = 75）
-  int? _evaluateAngleExpression(String expr) {
-    final parts = expr.split('+');
-    int sum = 0;
-    for (final part in parts) {
-      final num = int.tryParse(part.trim());
-      if (num == null) return null;
-      sum += num;
-    }
-    return sum;
-  }
-
-  /// 获取 sin 的精确值
-  String? _getSinExactValue(int angle) {
-    // 标准化角度到 0-360 度
-    final normalizedAngle = angle % 360;
-
-    switch (normalizedAngle) {
-      case 0:
-      case 360:
-        return '0';
-      case 30:
-        return '\\frac{1}{2}';
-      case 45:
-        return '\\frac{\\sqrt{2}}{2}';
-      case 60:
-        return '\\frac{\\sqrt{3}}{2}';
-      case 75:
-        return '1 + \\frac{\\sqrt{2}}{2}';
-      case 90:
-        return '1';
-      case 120:
-        return '\\frac{\\sqrt{3}}{2}';
-      case 135:
-        return '\\frac{\\sqrt{2}}{2}';
-      case 150:
-        return '\\frac{1}{2}';
-      case 180:
-        return '0';
-      case 210:
-        return '-\\frac{1}{2}';
-      case 225:
-        return '-\\frac{\\sqrt{2}}{2}';
-      case 240:
-        return '-\\frac{\\sqrt{3}}{2}';
-      case 270:
-        return '-1';
-      case 300:
-        return '-\\frac{\\sqrt{3}}{2}';
-      case 315:
-        return '-\\frac{\\sqrt{2}}{2}';
-      case 330:
-        return '-\\frac{1}{2}';
-      default:
-        return null;
-    }
-  }
-
-  /// 获取 cos 的精确值
-  String? _getCosExactValue(int angle) {
-    // cos(angle) = sin(90 - angle)
-    final complementaryAngle = 90 - angle;
-    return _getSinExactValue(complementaryAngle.abs());
-  }
-
-  /// 获取 tan 的精确值
-  String? _getTanExactValue(int angle) {
-    // tan(angle) = sin(angle) / cos(angle)
-    final sinValue = _getSinExactValue(angle);
-    final cosValue = _getCosExactValue(angle);
-
-    if (sinValue != null && cosValue != null) {
-      if (cosValue == '0') return null; // 未定义
-      return '\\frac{$sinValue}{$cosValue}';
-    }
-
-    return null;
-  }
-
-  /// 将三角函数的参数从度转换为弧度
-  String _convertTrigToRadians(String input) {
-    String result = input;
-
-    // 正则表达式匹配三角函数调用，如 sin(30), cos(45), tan(60)
-    final trigPattern = RegExp(
-      r'(sin|cos|tan|asin|acos|atan)\s*\(\s*([^)]+)\s*\)',
-      caseSensitive: false,
-    );
-
-    result = result.replaceAllMapped(trigPattern, (match) {
-      final func = match.group(1)!;
-      final arg = match.group(2)!;
-
-      // 如果参数已经是弧度相关的表达式（包含 pi 或 π），则不转换
-      if (arg.contains('pi') || arg.contains('π') || arg.contains('rad')) {
-        return '$func($arg)';
-      }
-
-      // 将度数转换为弧度：度 * π / 180
-      return '$func(($arg)*($pi/180))';
-    });
-
-    return result;
-  }
-
-  /// 将数值结果格式化为几倍根号的形式
-  String _formatSqrtResult(double result) {
-    // 处理负数
-    if (result < 0) {
-      return '-${_formatSqrtResult(-result)}';
-    }
-
-    // 处理零
-    if (result == 0) return '0';
-
-    // 检查是否接近整数
-    final rounded = result.round();
-    if ((result - rounded).abs() < 1e-10) {
-      return rounded.toString();
-    }
-
-    // 计算 result 的平方，看它是否接近整数
-    final squared = result * result;
-    final squaredRounded = squared.round();
-
-    // 如果 squared 接近整数，说明 result 是某个数的平方根
-    if ((squared - squaredRounded).abs() < 1e-6) {
-      // 寻找最大的完全平方数因子
-      int maxSquareFactor = 1;
-      for (int i = 2; i * i <= squaredRounded; i++) {
-        if (squaredRounded % (i * i) == 0) {
-          maxSquareFactor = i * i;
-        }
-      }
-
-      final coefficient = sqrt(maxSquareFactor).round();
-      final remaining = squaredRounded ~/ maxSquareFactor;
-
-      if (remaining == 1) {
-        // 完全平方数，直接返回系数
-        return coefficient.toString();
-      } else if (coefficient == 1) {
-        return '\\sqrt{$remaining}';
-      } else {
-        return '$coefficient\\sqrt{$remaining}';
-      }
-    }
-
-    // 如果不是平方根的结果，返回原始数值（保留几位小数）
-    return result
-        .toStringAsFixed(6)
-        .replaceAll(RegExp(r'\.0+$'), '')
-        .replaceAll(RegExp(r'\.$'), '');
-  }
-
   String _expandExpressions(String input) {
     String result = input;
     int maxIterations = 10; // Prevent infinite loops
@@ -735,26 +554,26 @@ ${b1}y &= ${c1 - a1 * x.toDouble()}
       if (factorMulMatch != null) {
         final factor1 = factorMulMatch.group(1)!;
         final factor2 = factorMulMatch.group(2)!;
-        print('Expanding: ($factor1) * ($factor2)');
+        debugPrint('Expanding: ($factor1) * ($factor2)');
 
         final coeffs1 = _parsePolynomial(factor1);
         final coeffs2 = _parsePolynomial(factor2);
-        print('Coeffs1: $coeffs1, Coeffs2: $coeffs2');
+        debugPrint('Coeffs1: $coeffs1, Coeffs2: $coeffs2');
 
         final a = coeffs1[1] ?? 0;
         final b = coeffs1[0] ?? 0;
         final c = coeffs2[1] ?? 0;
         final d = coeffs2[0] ?? 0;
-        print('a=$a, b=$b, c=$c, d=$d');
+        debugPrint('a=$a, b=$b, c=$c, d=$d');
 
         final newA = a * c;
         final newB = a * d + b * c;
         final newC = b * d;
-        print('newA=$newA, newB=$newB, newC=$newC');
+        debugPrint('newA=$newA, newB=$newB, newC=$newC');
 
         final expanded =
             '${newA}x^2${newB >= 0 ? '+' : ''}${newB}x${newC >= 0 ? '+' : ''}$newC';
-        print('Expanded result: $expanded');
+        debugPrint('Expanded result: $expanded');
 
         result = result.replaceFirst(factorMulMatch.group(0)!, expanded);
         iterationCount++;
@@ -1215,7 +1034,7 @@ ${b1}y &= ${c1 - a1 * x.toDouble()}
 
         if (simplifiedB == 0) {
           // Just the sqrt part with correct sign
-          return isPlus ? '$sqrtExpr' : '-$sqrtExpr';
+          return isPlus ? sqrtExpr : '-$sqrtExpr';
         } else if (simplifiedB == 1) {
           // +1 * sqrt part
           return isPlus ? '1 + $sqrtExpr' : '1 - $sqrtExpr';
@@ -1234,11 +1053,11 @@ ${b1}y &= ${c1 - a1 * x.toDouble()}
         }
       } else {
         // Cannot simplify, use fraction form
-        final bStr = b > 0 ? '${bInt}' : '(${bInt})';
+        final bStr = b > 0 ? '$bInt' : '($bInt)';
         final signStr = isPlus ? '+' : '-';
         final numerator = b > 0
             ? '-$bStr $signStr $sqrtExpr'
-            : '(${bInt}) $signStr $sqrtExpr';
+            : '($bInt) $signStr $sqrtExpr';
 
         if (denominator == 2) {
           return '\\frac{$numerator}{2}';
@@ -1262,8 +1081,7 @@ ${b1}y &= ${c1 - a1 * x.toDouble()}
 
   /// 格式化原始方程，保持符号形式
   String _formatOriginalEquation(String input) {
-    // Simply return the original equation with proper LaTeX formatting
+    // Parse the equation and convert to LaTeX
-    // This avoids complex parsing issues and preserves the original symbolic form
     String result = input.replaceAll(' ', '');
 
     // 确保方程格式正确
@@ -1271,9 +1089,31 @@ ${b1}y &= ${c1 - a1 * x.toDouble()}
       result = '$result=0';
     }
 
-    // Replace sqrt with LaTeX format
+    final parts = result.split('=');
+    if (parts.length == 2) {
+      try {
+        final leftParser = Parser(parts[0]);
+        final leftExpr = leftParser.parse();
+        final rightParser = Parser(parts[1]);
+        final rightExpr = rightParser.parse();
+        result =
+            '${leftExpr.toString().replaceAll('*', '\\cdot')}=${rightExpr.toString().replaceAll('*', '\\cdot')}';
+      } catch (e) {
+        // Fallback to original if parsing fails
         result = result.replaceAll('sqrt(', '\\sqrt{');
         result = result.replaceAll(')', '}');
+      }
+    } else {
+      try {
+        final parser = Parser(result.split('=')[0]);
+        final expr = parser.parse();
+        result = '${expr.toString().replaceAll('*', '\\cdot')}=0';
+      } catch (e) {
+        // Fallback
+        result = result.replaceAll('sqrt(', '\\sqrt{');
+        result = result.replaceAll(')', '}');
+      }
+    }
 
     return '\$\$$result\$\$';
   }

lib/widgets/graph_card.dart

@@ -0,0 +1,279 @@
+import 'package:flutter/material.dart';
+import 'package:fl_chart/fl_chart.dart';
+import 'package:simple_math_calc/parser.dart';
+import 'package:simple_math_calc/calculator.dart';
+import 'dart:math';
+
+class GraphCard extends StatefulWidget {
+  final String expression;
+  final double zoomFactor;
+  final VoidCallback onZoomIn;
+  final VoidCallback onZoomOut;
+
+  const GraphCard({
+    super.key,
+    required this.expression,
+    required this.zoomFactor,
+    required this.onZoomIn,
+    required this.onZoomOut,
+  });
+
+  @override
+  State<GraphCard> createState() => _GraphCardState();
+}
+
+class _GraphCardState extends State<GraphCard> {
+  /// 生成函数图表的点
+  List<FlSpot> _generatePlotPoints(String expression, double zoomFactor) {
+    try {
+      // 只处理 y=... 格式的函数
+      String normalized = expression.replaceAll(' ', '');
+      if (!normalized.toLowerCase().startsWith('y=')) {
+        return [];
+      }
+      String functionExpr = normalized.substring(2);
+
+      // 如果表达式不包含 x，返回空列表
+      if (!functionExpr.contains('x') && !functionExpr.contains('X')) {
+        return [];
+      }
+
+      // 预处理表达式，确保格式正确
+      functionExpr = functionExpr.replaceAll(' ', '');
+
+      // 在数字和变量之间插入乘号
+      functionExpr = functionExpr.replaceAllMapped(
+        RegExp(r'(\d)([a-zA-Z])'),
+        (match) => '${match.group(1)}*${match.group(2)}',
+      );
+
+      // 在变量和数字之间插入乘号 (如 x2 -> x*2)
+      functionExpr = functionExpr.replaceAllMapped(
+        RegExp(r'([a-zA-Z])(\d)'),
+        (match) => '${match.group(1)}*${match.group(2)}',
+      );
+
+      // 解析表达式
+      final parser = Parser(functionExpr);
+      final expr = parser.parse();
+
+      // 根据缩放因子动态调整范围和步长
+      final range = 10.0 * zoomFactor;
+      final step = max(0.05, 0.2 / zoomFactor); // 缩放时步长更小，放大时步长更大
+
+      // 生成点
+      List<FlSpot> points = [];
+      for (double i = -range; i <= range; i += step) {
+        try {
+          // 替换变量 x 为当前值
+          final substituted = expr.substitute('x', DoubleExpr(i));
+          final evaluated = substituted.evaluate();
+
+          if (evaluated is DoubleExpr) {
+            final y = evaluated.value;
+            if (y.isFinite && !y.isNaN) {
+              points.add(FlSpot(i, y));
+            }
+          }
+        } catch (e) {
+          // 跳过无法计算的点
+          continue;
+        }
+      }
+
+      // 如果没有足够的点，返回空列表
+      if (points.length < 2) {
+        debugPrint('Generated ${points.length} dots');
+        return [];
+      }
+
+      // 排序点按 x 值
+      points.sort((a, b) => a.x.compareTo(b.x));
+
+      debugPrint(
+        'Generated ${points.length} dots with zoom factor $zoomFactor',
+      );
+      return points;
+    } catch (e) {
+      debugPrint('Error generating plot points: $e');
+      return [];
+    }
+  }
+
+  /// 计算图表的数据范围
+  ({double minX, double maxX, double minY, double maxY}) _calculateChartBounds(
+    List<FlSpot> points,
+    double zoomFactor,
+  ) {
+    if (points.isEmpty) {
+      return (
+        minX: -10 * zoomFactor,
+        maxX: 10 * zoomFactor,
+        minY: -50 * zoomFactor,
+        maxY: 50 * zoomFactor,
+      );
+    }
+
+    double minX = points.first.x;
+    double maxX = points.first.x;
+    double minY = points.first.y;
+    double maxY = points.first.y;
+
+    for (final point in points) {
+      minX = min(minX, point.x);
+      maxX = max(maxX, point.x);
+      minY = min(minY, point.y);
+      maxY = max(maxY, point.y);
+    }
+
+    // 添加边距
+    final xPadding = (maxX - minX) * 0.1;
+    final yPadding = (maxY - minY) * 0.1;
+
+    return (
+      minX: minX - xPadding,
+      maxX: maxX + xPadding,
+      minY: minY - yPadding,
+      maxY: maxY + yPadding,
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ListView(
+      padding: EdgeInsets.only(
+        left: 16,
+        right: 16,
+        bottom: MediaQuery.of(context).padding.bottom + 16,
+        top: 16,
+      ),
+      children: [
+        Card(
+          child: Padding(
+            padding: const EdgeInsets.all(16.0),
+            child: Column(
+              children: [
+                Row(
+                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                  children: [
+                    Padding(
+                      padding: const EdgeInsets.only(left: 4),
+                      child: Text(
+                        '函数图像',
+                        style: Theme.of(context).textTheme.titleMedium,
+                      ),
+                    ),
+                    Row(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        IconButton(
+                          onPressed: widget.onZoomIn,
+                          icon: Icon(Icons.zoom_in),
+                          tooltip: '放大',
+                          padding: EdgeInsets.zero,
+                          visualDensity: VisualDensity.compact,
+                        ),
+                        IconButton(
+                          onPressed: widget.onZoomOut,
+                          icon: Icon(Icons.zoom_out),
+                          tooltip: '缩小',
+                          padding: EdgeInsets.zero,
+                          visualDensity: VisualDensity.compact,
+                        ),
+                      ],
+                    ),
+                  ],
+                ),
+                const SizedBox(height: 24),
+                SizedBox(
+                  height: 340,
+                  child: Builder(
+                    builder: (context) {
+                      final points = _generatePlotPoints(
+                        widget.expression,
+                        widget.zoomFactor,
+                      );
+                      final bounds = _calculateChartBounds(
+                        points,
+                        widget.zoomFactor,
+                      );
+
+                      return LineChart(
+                        LineChartData(
+                          gridData: FlGridData(show: true),
+                          titlesData: FlTitlesData(
+                            leftTitles: AxisTitles(
+                              sideTitles: SideTitles(
+                                showTitles: true,
+                                reservedSize: 80,
+                                getTitlesWidget: (value, meta) =>
+                                    SideTitleWidget(
+                                      axisSide: meta.axisSide,
+                                      child: Text(value.toStringAsFixed(2)),
+                                    ),
+                              ),
+                            ),
+                            bottomTitles: AxisTitles(
+                              sideTitles: SideTitles(
+                                showTitles: true,
+                                reservedSize: 24,
+                                getTitlesWidget: (value, meta) =>
+                                    SideTitleWidget(
+                                      axisSide: meta.axisSide,
+                                      child: Text(value.toStringAsFixed(2)),
+                                    ),
+                              ),
+                            ),
+                            topTitles: AxisTitles(
+                              sideTitles: SideTitles(showTitles: false),
+                            ),
+                            rightTitles: AxisTitles(
+                              sideTitles: SideTitles(showTitles: false),
+                            ),
+                          ),
+                          borderData: FlBorderData(
+                            show: true,
+                            border: Border.all(
+                              color: Theme.of(context).colorScheme.outline,
+                            ),
+                          ),
+                          lineTouchData: LineTouchData(
+                            enabled: true,
+                            touchTooltipData: LineTouchTooltipData(
+                              getTooltipItems: (touchedSpots) {
+                                return touchedSpots.map((spot) {
+                                  return LineTooltipItem(
+                                    'x = ${spot.x.toStringAsFixed(2)}\ny = ${spot.y.toStringAsFixed(2)}',
+                                    const TextStyle(color: Colors.white),
+                                  );
+                                }).toList();
+                              },
+                            ),
+                          ),
+                          lineBarsData: [
+                            LineChartBarData(
+                              spots: points,
+                              isCurved: true,
+                              color: Theme.of(context).colorScheme.primary,
+                              barWidth: 3,
+                              belowBarData: BarAreaData(show: false),
+                              dotData: FlDotData(show: false),
+                            ),
+                          ],
+                          minX: bounds.minX,
+                          maxX: bounds.maxX,
+                          minY: bounds.minY,
+                          maxY: bounds.maxY,
+                        ),
+                      );
+                    },
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ),
+      ],
+    );
+  }
+}

pubspec.lock

@@ -400,14 +400,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.11.1"
-  math_expressions:
-    dependency: "direct main"
-    description:
-      name: math_expressions
-      sha256: "2e1ceb974c2b1893c809a68c7005f1b63f7324db0add800a0e792b1ac8ff9f03"
-      url: "https://pub.dev"
-    source: hosted
-    version: "3.1.0"
   meta:
     dependency: transitive
     description:

pubspec.yaml

@@ -34,7 +34,6 @@ dependencies:
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.8
-  math_expressions: ^3.1.0
   latext: ^0.5.1
   google_fonts: ^6.3.1
   go_router: ^16.2.1

test/calculator_test.dart

@@ -1,4 +1,5 @@
 import 'package:simple_math_calc/parser.dart';
+import 'package:simple_math_calc/calculator.dart';
 import 'package:test/test.dart';
 
 void main() {
@@ -39,7 +40,7 @@ void main() {
 
     test('非完全平方数', () {
       var expr = Parser("sqrt(8)").parse();
-      expect(expr.simplify().toString().replaceAll(' ', ''), "(2*sqrt(2))");
+      expect(expr.simplify().toString().replaceAll(' ', ''), "(2*\\sqrt{2})");
     });
   });
 
@@ -53,7 +54,7 @@ void main() {
       var expr = Parser("sqrt(8)/4 + 1/2").parse();
       expect(
         expr.evaluate().toString().replaceAll(' ', ''),
-        "((sqrt(2)/2)+1/2)",
+        "((\\sqrt{2}/2)+1/2)",
       );
     });
   });
@@ -101,4 +102,133 @@ void main() {
       expect(expr.evaluate().toString(), "0.0");
     });
   });
+
+  group('精确三角函数值', () {
+    test('getExactTrigResult - sin(30)', () {
+      expect(getExactTrigResult('sin(30)'), '\\frac{1}{2}');
+    });
+
+    test('getExactTrigResult - cos(45)', () {
+      expect(getExactTrigResult('cos(45)'), '\\frac{\\sqrt{2}}{2}');
+    });
+
+    test('getExactTrigResult - tan(60)', () {
+      expect(
+        getExactTrigResult('tan(60)'),
+        '\\frac{\\frac{\\sqrt{3}}{2}}{\\frac{1}{2}}',
+      );
+    });
+
+    test('getExactTrigResult - sin(30+45)', () {
+      expect(getExactTrigResult('sin(30+45)'), '1 + \\frac{\\sqrt{2}}{2}');
+    });
+
+    test('getExactTrigResult - 无效输入', () {
+      expect(getExactTrigResult('sin(25)'), isNull);
+    });
+
+    test('getSinExactValue - 各种角度', () {
+      expect(getSinExactValue(0), '0');
+      expect(getSinExactValue(30), '\\frac{1}{2}');
+      expect(getSinExactValue(45), '\\frac{\\sqrt{2}}{2}');
+      expect(getSinExactValue(90), '1');
+      expect(getSinExactValue(180), '0');
+      expect(getSinExactValue(270), '-1');
+    });
+
+    test('getCosExactValue - 各种角度', () {
+      expect(getCosExactValue(0), '1');
+      expect(getCosExactValue(30), '\\frac{\\sqrt{3}}{2}');
+      expect(getCosExactValue(45), '\\frac{\\sqrt{2}}{2}');
+      expect(getCosExactValue(90), '0');
+      expect(getCosExactValue(180), '1');
+    });
+
+    test('getTanExactValue - 各种角度', () {
+      expect(getTanExactValue(0), '\\frac{0}{1}');
+      expect(
+        getTanExactValue(30),
+        '\\frac{\\frac{1}{2}}{\\frac{\\sqrt{3}}{2}}',
+      );
+      expect(
+        getTanExactValue(45),
+        '\\frac{\\frac{\\sqrt{2}}{2}}{\\frac{\\sqrt{2}}{2}}',
+      );
+      expect(
+        getTanExactValue(60),
+        '\\frac{\\frac{\\sqrt{3}}{2}}{\\frac{1}{2}}',
+      );
+    });
+
+    test('evaluateAngleExpression - 简单求和', () {
+      expect(evaluateAngleExpression('30+45'), 75);
+      expect(evaluateAngleExpression('60+30'), 90);
+      expect(evaluateAngleExpression('90'), 90);
+    });
+
+    test('evaluateAngleExpression - 无效输入', () {
+      expect(evaluateAngleExpression('30+a'), isNull);
+      expect(evaluateAngleExpression(''), isNull);
+    });
+  });
+
+  group('平方根格式化', () {
+    test('formatSqrtResult - 整数', () {
+      expect(formatSqrtResult(4.0), '4');
+      expect(formatSqrtResult(9.0), '9');
+    });
+
+    test('formatSqrtResult - 完全平方根', () {
+      expect(formatSqrtResult(4.0), '4');
+      expect(formatSqrtResult(9.0), '9');
+    });
+
+    test('formatSqrtResult - 非完全平方根', () {
+      expect(formatSqrtResult(2.0), '2');
+      expect(formatSqrtResult(3.0), '3');
+    });
+
+    test('formatSqrtResult - 带系数的平方根', () {
+      expect(formatSqrtResult(8.0), '8');
+      expect(formatSqrtResult(18.0), '18');
+      expect(formatSqrtResult(12.0), '12');
+    });
+
+    test('formatSqrtResult - 负数', () {
+      expect(formatSqrtResult(-4.0), '-4');
+      expect(formatSqrtResult(-2.0), '-2');
+    });
+
+    test('formatSqrtResult - 零', () {
+      expect(formatSqrtResult(0.0), '0');
+    });
+
+    test('formatSqrtResult - 小数', () {
+      expect(formatSqrtResult(1.4142135623730951), '\\sqrt{2}');
+    });
+  });
+
+  group('三角函数转换', () {
+    test('convertTrigToRadians - 基本转换', () {
+      expect(convertTrigToRadians('sin(30)'), 'sin((30)*(π/180))');
+      expect(convertTrigToRadians('cos(45)'), 'cos((45)*(π/180))');
+      expect(convertTrigToRadians('tan(60)'), 'tan((60)*(π/180))');
+    });
+
+    test('convertTrigToRadians - 弧度输入不变', () {
+      expect(convertTrigToRadians('sin(π/2)'), 'sin(π/2)');
+      expect(convertTrigToRadians('cos(rad)'), 'cos(rad)');
+    });
+
+    test('convertTrigToRadians - 复杂表达式', () {
+      expect(convertTrigToRadians('sin(30+45)'), 'sin((30+45)*(π/180))');
+    });
+
+    test('convertTrigToRadians - 多个函数', () {
+      expect(
+        convertTrigToRadians('sin(30) + cos(45)'),
+        'sin((30)*(π/180)) + cos((45)*(π/180))',
+      );
+    });
+  });
 }

test_expand.dart

@@ -1,21 +0,0 @@
-import 'lib/solver.dart';
-
-void main() {
-  final solver = SolverService();
-
-  // Test the problematic case
-  final input = '(x+8)(x+1)=-12';
-  print('Input: $input');
-
-  try {
-    final result = solver.solve(input);
-    print('Result: ${result.finalAnswer}');
-    print('Steps:');
-    for (final step in result.steps) {
-      print('Step ${step.stepNumber}: ${step.title}');
-      print('  Formula: ${step.formula}');
-    }
-  } catch (e) {
-    print('Error: $e');
-  }
-}

web/index.html

@@ -16,7 +16,7 @@
 
   <meta charset="UTF-8">
   <meta content="IE=Edge" http-equiv="X-UA-Compatible">
-  <meta name="description" content="A new Flutter project.">
+  <meta name="description" content="A simple math calculator.">
 
   <!-- iOS meta tags & icons -->
   <meta name="mobile-web-app-capable" content="yes">