mossadal/math-parser

PHP parser for mathematical expressions, including elementary functions, variables and implicit multiplication. Also supports symbolic differentiation.

Friday, March 9, 2018
by mossadal
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PHP
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The README.md

math-parser

$Latest Stable Version$ $Total Downloads$ $License$ $Code Climate$ , _(*1)

DESCRIPTION

PHP parser and evaluator library for mathematical expressions., _(*2)

Intended use: safe and reasonably efficient evaluation of user submitted formulas. The library supports basic arithmetic and elementary functions, as well as variables and extra functions., _(*3)

The lexer and parser produces an abstract syntax tree (AST) that can be traversed using a tree interpreter. The math-parser library ships with three interpreters:, _(*4)

an evaluator computing the value of the given expression.
a differentiator transforming the AST into a (somewhat) simplied AST representing the derivative of the supplied expression.
a rudimentary LaTeX output generator, useful for pretty printing expressions using MathJax

EXAMPLES

It is possible to fine-tune the lexer and parser, but the library ships with a StdMathParser class, capable of tokenizing and parsing standard mathematical expressions, including arithmetical operations as well as elementary functions., _(*5)

~~~{.php} use MathParser\StdMathParser; use MathParser\Interpreting\Evaluator;, _(*6)

$parser = new StdMathParser();, _(*7)

// Generate an abstract syntax tree $AST = $parser->parse('1+2');, _(*8)

// Do something with the AST, e.g. evaluate the expression: $evaluator = new Evaluator();, _(*9)

$value = $AST->accept($evaluator); echo $value;, _(*10)


More interesting example, containing variables:

~~~{.php}
$AST = $parser->parse('x+sqrt(y)');

$evaluator->setVariables([ 'x' => 2, 'y' => 3 ]);
$value = $AST->accept($evaluator);

We can do other things with the AST. The library ships with a differentiator, computing the (symbolic) derivative with respect to a given variable., _(*11)

~~~{.php} use MathParser\Interpreting\Differentiator;, _(*12)

$differentiator = new Differentiator('x'); $f = $parser->parse('exp(2x)-xy'); $df = $f->accept($differentiator);, _(*13)

// $df now contains the AST of '2*exp(x)-y' and can be evaluated further $evaluator->setVariables([ 'x' => 1, 'y' => 2 ]); $df->accept($evaluator); ~~~, _(*14)

Implicit multiplication

Another helpful feature is that the parser understands implicit multiplication. An expression as 2x is parsed the same as 2*x and xsin(x)cos(x)^2 is parsed as x*sin(x)*cos(x)^2., _(*15)

Note that implicit multiplication has the same precedence as explicit multiplication. In particular, xy^2z is parsed as x*y^2*z and not as x*y^(2*z)., _(*16)

To make full use of implicit multiplication, the standard lexer only allows one-letter variables. (Otherwise, we wouldn't know if xy should be parsed as x*y or as the single variable xy)., _(*17)

DOCUMENTATION

For complete documentation, see the github.io project page, _(*18)

THANKS

The Lexer is based on the lexer described by Marc-Oliver Fiset in his blog., _(*19)

The parser is a version of the "Shunting yard" algorithm, described for example by Theodore Norvell., _(*20)

The Versions

09/03 2018

dev-master

9999999-dev https://github.com/mossadal/math-parser

PHP parser for mathematical expressions, including elementary functions, variables and implicit multiplication. Also supports symbolic differentiation.

library math-parser

PHP parser for mathematical expressions, including elementary functions, variables and implicit multiplication. Also supports symbolic differentiation.

mossadal/math-parser

The README.md

math-parser

DESCRIPTION

EXAMPLES

Implicit multiplication

DOCUMENTATION

THANKS

The Versions

dev-master

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The Development Requires

by Frank Wikström

v1.3.13

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by Frank Wikström

v1.3.12

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by Frank Wikström

v1.3.11

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by Frank Wikström

v1.3.10

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by Frank Wikström

v1.3.9

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by Frank Wikström

v1.3.8

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by Frank Wikström

v1.3.7

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by Frank Wikström

v1.3.6

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by Frank Wikström

v1.3.5

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by Frank Wikström

v1.3.4

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by Frank Wikström

v1.3.3

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by Frank Wikström

v1.3.2

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by Frank Wikström

dev-develop

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by Frank Wikström

v1.3.1

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by Frank Wikström

v1.3.0

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by Frank Wikström

v1.2.3

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by Frank Wikström

v1.2.2