MathExpressionParser

A lightweight customizable math expression parsing library that supports custom functions and variables, with a complete error handling system(ParserException).

Getting Started

Evaluating a expression

MathExpression expr = new("1 * (2 + 3) - (4 * 5 * (6 + 7))");
double value = expr.Evaluate(); // value is -255

MathExpression expr = new("1! * 2! * 3! * 4!");
double value = expr.Evaluate(); // value is 288

MathExpression expr = new("sin(90 torad)");
double value = expr.Evaluate(); // value is 1

MathExpression expr = new("sqrt(1 + sin(pi / 2) * 3)");
double value = expr.Evaluate(); // value is 2

MathExpression expr = new("log(log(3.2e+2, -(-1e1)), sqrt(1E-4))");
double value = expr.Evaluate(); // value is -0.19941686566

Supported built-in operators, functions, and constants

The number in the parentheses is the number of arguments that function takes.

All trigonometric functions are in radians. Use torad to convert degrees to radians.

Type	Name	Description
Binary	+	Addition
Binary	-	Subtraction
Prefix unary	-	Negation
Binary	*	Multiplication
Binary	/	Division
Binary	^	Power
Binary	%	Modulo
Constant	pi	π
Constant	e	Euler's number
Function(1)	sqrt	Square root
Function(1)	sin	Sine
Function(1)	asin	Arc sine
Function(1)	cos	Cosine
Function(1)	acos	Arc cosine
Function(1)	tan	Tangent
Function(1)	atan	Arc tangent
Function(1)	csc	Cosecant
Function(1)	acsc	Arc cosecant
Function(1)	sec	Secant
Function(1)	asec	Arc secant
Function(1)	cot	Cotangent
Function(1)	acot	Arc cotangent
Function(1)	sinh	Hyperbolic sine
Function(1)	asinh	Hyperbolic arc sine
Function(1)	cosh	Hyperbolic cosine
Function(1)	acosh	Hyperbolic arc cosine
Function(1)	tanh	Hyperbolic tangent
Function(1)	atanh	Hyperbolic arc tangent
Function(1)	csch	Hyperbolic cosecant
Function(1)	acsch	Hyperbolic arc cosecant
Function(1)	sech	Hyperbolic secant
Function(1)	asech	Hyperbolic arc secant
Function(1)	coth	Hyperbolic cotangent
Function(1)	acoth	Hyperbolic arc cotangent
Function(2)	P	Permutation
Function(2)	C	Combination
Function(2)	H	H(x, y) = C(x + y - 1, x - 1) = C(x + y - 1, y)
Function(2)	log	Logarithm. The second argument is the base.
Function(1)	log10	Logarithm base 10
Function(1)	log2	Logarithm base 2
Function(1)	ln	Natural logarithm
Function(1)	ceil	Least integer not less than
Function(1)	floor	Greatest integer not greater than
Function(1)	round	Round decimal places
Function(1)	abs	Absolute value
Function(any)	min	Returns the least value of the arguments. If no arguments are given, returns 0.
Function(any)	max	Returns the greatest value of the arguments. If no arguments are given, returns 0.
Postfix unary	!	Factorial
Postfix unary	torad	Converts degrees to radians
Postfix unary	todeg	Converts radians to degrees

Adding custom functions and constants

MathExpression expr = new("f(x)");
expr.CustomFunctions.Add(new FunctionalOperator("f", x => x[0] * 2, 1));
expr.CustomConstants.Add(new ConstantOperator("x", 100));
double value = expr.Evaluate(); // value is 200

Error handling

MathExpression expr = new("sin(1,)");
Console.WriteLine(expr.Validate()?.Context);
// prints ParserExceptionContext { Position = 6, Type = UnexpectedClosingParenthesis }

MathExpression expr = new("2sin(2)");
Console.WriteLine(expr.Validate()?.Context);
// prints ParserExceptionContext { Position = 1, Type = UnexpectedFunctionalOperator }

MathExpression expr = new("cos(1, 2)");
Console.WriteLine(expr.Validate()?.Context);
// prints ParserExceptionContext { Position = 0, Type = IncorrectArgumentCount }

MathExpression expr = new("tan(pipi)");
Console.WriteLine(expr.Validate()?.Context);
// prints ParserExceptionContext { Position = 4, Type = UnknownOperator }

All error types

Type	Description
InvalidNumberFormat	An error where a number with an invalid format was found in a MathExpression.
IncorrectArgumentCount	An error where either too many or too few arguments were passed to a FunctionalOperator.
InvalidCustomFunctionName	An error where some of the custom functions provided have names that either start with a number, are empty, or contain characters that are not alphanumeric or are not underscores.
NullCustomFunction	An error where MathExpression.CustomFunctions contains a null element.
InvalidCustomConstantName	An error where some of the custom constants provided have names that either start with a number, are empty, or contain characters that are not alphanumeric or are not underscores.
NullCustomConstant	An error where MathExpression.CustomConstants contain a null element.
NaNConstant	An error where MathExpression.CustomConstants have a ConstantOperator.Value of double.NaN.
ConflictingNames	An error where two Operators in a MathExpression share the same name.
UnexpectedBinaryOperator	An error where a BinaryOperator is used incorrectly.
TooManyOpeningParentheses	An error where a opening parenthesiis is used without a corresponding opening parenthesis.
UnexpectedClosingParenthesis	An error where a closing parenthesis is used incorrectly, or where a closing parenthesis is used without a corresponding opening parenthesis.
UnexpectedComma	An error where a comma is used incorrectly.
UnexpectedConstantOperator	An error where a ConstantOperator is used incorrectly.
UnexpectedFunctionalOperator	An error where a FunctionalOperator is used incorrectly.
UnexpectedNumber	An error where a number is used incorrectly.
UnexpectedOpeningParenthesis	An error where a opening parenthesis is used incorrectly.
UnexpectedPostfixUnaryOperator	An error where a PostfixUnaryOperator is used incorrectly.
UnexpectedPrefixUnaryOperator	An error where a PrefixUnaryOperator is used incorrectly.
UnknownOperator	An error where an unknown Operator is used in a MathExpression.
UnexpectedNewline	An error where a MathExpression ended unexpectedly.

Complete Docs

For the complete auto-generated documentation, see here. (The docs generation tool Vsxmd currently doesn't work with <inheritdoc> tags and will just leave them empty or write "Inherited from parent.")