muParser is an extensible high-performance math expression parser library written in C++

C++

C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...

. It works by transforming a mathematical expression into bytecode

Bytecode

Bytecode, also known as p-code , is a term which has been used to denote various forms of instruction sets designed for efficient execution by a software interpreter as well as being suitable for further compilation into machine code...

 and precalculating constant parts of the expression.
It runs on both 32-bit

32-bit

The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....

 and 64-bit

64-bit

64-bit is a word size that defines certain classes of computer architecture, buses, memory and CPUs, and by extension the software that runs on them. 64-bit CPUs have existed in supercomputers since the 1970s and in RISC-based workstations and servers since the early 1990s...

 architectures

Computer architecture

In computer science and engineering, computer architecture is the practical art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals and the formal modelling of those systems....

 and has been tested using Visual C++

Visual C++

Microsoft Visual C++ is a commercial , integrated development environment product from Microsoft for the C, C++, and C++/CLI programming languages...

 and GCC

GNU Compiler Collection

The GNU Compiler Collection is a compiler system produced by the GNU Project supporting various programming languages. GCC is a key component of the GNU toolchain...

. The library is open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 and distributed under the MIT License

MIT License

The MIT License is a free software license originating at the Massachusetts Institute of Technology . It is a permissive license, meaning that it permits reuse within proprietary software provided all copies of the licensed software include a copy of the MIT License terms...

.

Overview

• Easy to use (only a few lines of code to evaluate an expression)
• Extremely fast
• User-defined operators (binary, postfix and infix)
• User-defined functions
• User-defined constants
• User-defined variables
• Custom value recognition callbacks
• Default implementation
  • 26 predefined functions
  • 15 predefined operators
  • Supports numerical differentiation with respect to a given variable
  • Assignment operator is supported
• Portability
  • Project / makefiles for MSVC, mingw, autoconf, bcc
  • ISO 14882 compliant code
  • DLL version usable from every language able to use function exported in C-style
• Unit support (postfix operators as unit multipliers)
• Localization (of argument separator, decimal separator, thousands separator)

Built-in Functions

Name	Argument Count	Explanation
sin	1	sine function
cos	1	cosine function
tan	1	tangens function
asin	1	arcus sine function
acos	1	arcus cosine function
atan	1	arcus tangens function
sinh	1	hyperbolic sine function
cosh	1	hyperbolic cosine
tanh	1	hyperbolic tangens function
asinh	1	hyperbolic arcus sine function
acosh	1	hyperbolic arcus tangens function
atanh	1	hyperbolic arcur tangens function
log2	1	logarithm to the base 2
log10	1	logarithm to the base 10
log	1	logarithm to the base 10
ln	1	logarithm to base e (2.71828...)
exp	1	e raised to the power of x
sqrt	1	square root of a value
sign	1	sign function -1 if x<0; 1 if x>0
rint	1	round to nearest integer
abs	1	absolute value
if	3	if ... then ... else ...
min	var.	min of all arguments
max	var.	max of all arguments
sum	var.	sum of all arguments
avg	var.	mean value of all arguments

Built-in operators

Operator	Meaning	Priority
=	assignment*
and	logical and	1
or	logical or	1
xor	logical xor	1
<=	less or equal	2
>=	greater or equal	2
!=	not equal	2
	equal	2
>	greater than	2
<	less than	2
+	addition	3
-	subtraction	3
*	multiplication	4
/	division	4
^	raise x to the power of y	5

*The assignment operator is special since it changes one of its arguments and can only be applied to variables.
Example Code

#include 

include "muParser.h"




// Function callback

double MyFunction(double a_fVal)

{

  return a_fVal*a_fVal;

}



// main program

int main(int argc, char* argv[])

{

  using namespace mu;



  try

  {

    double fVal = 1;

    Parser p;

    p.DefineVar("a", &fVal);

    p.DefineFun("MyFunc", MyFunction);

    p.SetExpr("MyFunc(a)*_pi+min(10,a)");

    std::cout << p.Eval << std::endl;

  }

  catch (Parser::exception_type &e)

  {

    std::cout << e.GetMsg << std::endl;

  }

  return 0;

}