string-math
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Evaluates a math expression from a string. Supports variables and custom operators.
V3 README can be found here: https://github.com/miroiu/string-math/tree/release-3.0.0
NEW! Boolean math example: https://github.com/miroiu/string-math/pull/6/files
String Math
Calculates the value of a math expression from a string returning a double. Supports variables, user defined operators and expression compilation.
double result = "1 * (2 - 3) ^ 2".Eval(); // 1
Variables
double result = "{a} + 2 * {b}".Substitute("a", 2).Substitute("b", 3).Result; // 8
Global variables
These variables are inherited and cannot be substituted.
MathExpr.AddVariable("PI", 3.1415926535897931);
double result = "1 + {PI}".Eval(); // 4.1415926535897931
Custom operators
Global operators
These operators are inherited and can be overidden.
MathExpr.AddOperator("abs", a => a > 0 ? a : -a);
double result = "abs -5".Eval(); // 5
// Operator precedence (you can specify an int for precedence)
MathExpr.AddOperator("max", (a, b) => a > b ? a : b, Precedence.Power);
double result = new MathExpr("2 * 3 max 4").Result; // 8
Local operators
These are applied only to the target expression.
MathExpr expr = "{PI} + 1";
expr.SetOperator("+", (a, b) => Math.Pow(a, b));
double result = expr; // 3.1415926535897931
double result2 = "{PI} + 1".Eval(); // 4.1415926535897931
Advanced
Extract variables
var expr = "{a} + {b} + {PI}".ToMathExpr();
var variables = expr.Variables; // { "a", "b", "PI" }
var localVariables = expr.LocalVariables; // { "a", "b" }
Compilation
Func<double, double> fn = "{a} + 2".ToMathExpr().Compile("a");
double result = fn(5); // 7
Conditional substitution
MathExpr expr = "1 / {a}".Substitute("a", 1);
double temp = expr.Result; // 1
if (someCondition) // true
expr.Substitute("a", 2);
double final = expr.Result; // 0.5
Sharing math context
MathExpr expr = "{PI} + 1";
expr.SetOperator("+", (a, b) => Math.Pow(a, b));
MathExpr expr2 = "3 + 2".ToMathExpr(expr.Context);
double result = "1 + 2 + 3".Eval(expr.Context);
Custom math context
var context = new MathContext(); // new MathContext(MathContext.Default); // to inherit from global
context.RegisterBinary("+", (a, b) => Math.Pow(a, b));
MathExpr expr = new MathExpr("{PI} + 1", context);
MathExpr expr2 = "3 + 2".ToMathExpr(context);
double result = "1 + 2 + 3".Eval(context);
Default operators
Binary
+ (addition)
- (subtraction)
* (multiplication)
/ (division)
% (remainder)
^ (power)
log (logarithm)
max (maximum)
min (minimum)
Unary
- (negation)
! (factorial)
sqrt (square root)
sin (sine)
asin (arcsine)
cos (cosine)
acos (arccosine)
tan (tangent)
atan (arctangent)
rad (convert degrees to radians)
deg (convert radians to degrees)
ceil (ceiling)
floor (floor)
round (rounding)
exp (e raised to power)
abs (absolute)