---
Hoa is a modular, extensible and
structured set of PHP libraries.
Moreover, Hoa aims at being a bridge between industrial and research worlds.
# Hoa\Math
[](https://webchat.freenode.net/?channels=#hoaproject)
[](https://gitter.im/hoaproject/central)
[](https://central.hoa-project.net/Documentation/Library/Math)
[](https://waffle.io/hoaproject/math)
This library provides tools around mathematical operations.
[Learn more](https://central.hoa-project.net/Documentation/Library/Math).
## Installation
With [Composer](https://getcomposer.org/), to include this library into
your dependencies, you need to
require [`hoa/math`](https://packagist.org/packages/hoa/math):
```sh
$ composer require hoa/math '~1.0'
```
For more installation procedures, please read [the Source
page](https://hoa-project.net/Source.html).
## Testing
Before running the test suites, the development dependencies must be installed:
```sh
$ composer install
```
Then, to run all the test suites:
```sh
$ vendor/bin/hoa test:run
```
For more information, please read the [contributor
guide](https://hoa-project.net/Literature/Contributor/Guide.html).
## Quick usage
We propose a quick overview of one feature: evaluation of arithmetical
expressions.
### Evaluation of arithmetical expressions
The `hoa://Library/Math/Arithmetic.pp` describes the form of an arithmetical
expression. Therefore, we will use the classical workflow when manipulating a
grammar, that involves the [`Hoa\Compiler`
library](https://central.hoa-project.net/Resource/Library/Compiler) and the
`Hoa\Math\Visitor\Arithmetic` class.
```php
// 1. Load the compiler.
$compiler = Hoa\Compiler\Llk::load(
new Hoa\File\Read('hoa://Library/Math/Arithmetic.pp')
);
// 2. Load the visitor, aka the “evaluator”.
$visitor = new Hoa\Math\Visitor\Arithmetic();
// 3. Declare the expression.
$expression = '1 / 2 / 3 + 4 * (5 * 2 - 6) * PI / avg(7, 8, 9)';
// 4. Parse the expression.
$ast = $compiler->parse($expression);
// 5. Evaluate.
var_dump(
$visitor->visit($ast)
);
/**
* Will output:
* float(6.4498519738463)
*/
// Bonus. Print the AST of the expression.
$dump = new Hoa\Compiler\Visitor\Dump();
echo $dump->visit($ast);
/**
* Will output:
* > #addition
* > > #division
* > > > token(number, 1)
* > > > #division
* > > > > token(number, 2)
* > > > > token(number, 3)
* > > #multiplication
* > > > token(number, 4)
* > > > #multiplication
* > > > > #group
* > > > > > #substraction
* > > > > > > #multiplication
* > > > > > > > token(number, 5)
* > > > > > > > token(number, 2)
* > > > > > > token(number, 6)
* > > > > #division
* > > > > > token(constant, PI)
* > > > > > #function
* > > > > > > token(id, avg)
* > > > > > > token(number, 7)
* > > > > > > token(number, 8)
* > > > > > > token(number, 9)
*/
```
We can add functions and constants on the visitor, thanks to the `addFunction`
and `addConstant` methods. Thus, we will add the `rand` function (with 2
parameters) and the `ANSWER` constant, set to 42:
```php
$visitor->addFunction('rand', function ($min, $max) {
return mt_rand($min, $max);
});
$visitor->addConstant('ANSWER', 42);
$expression = 'rand(ANSWER / 2, ANSWER * 2)'
var_dump(
$visitor->visit($compiler->parse($expression))
);
/**
* Could output:
* int(53)
*/
```
## Documentation
The
[hack book of `Hoa\Math`](https://central.hoa-project.net/Documentation/Library/Math) contains
detailed information about how to use this library and how it works.
To generate the documentation locally, execute the following commands:
```sh
$ composer require --dev hoa/devtools
$ vendor/bin/hoa devtools:documentation --open
```
More documentation can be found on the project's website:
[hoa-project.net](https://hoa-project.net/).
## Getting help
There are mainly two ways to get help:
* On the [`#hoaproject`](https://webchat.freenode.net/?channels=#hoaproject)
IRC channel,
* On the forum at [users.hoa-project.net](https://users.hoa-project.net).
## Contribution
Do you want to contribute? Thanks! A detailed [contributor
guide](https://hoa-project.net/Literature/Contributor/Guide.html) explains
everything you need to know.
## License
Hoa is under the New BSD License (BSD-3-Clause). Please, see
[`LICENSE`](https://hoa-project.net/LICENSE) for details.
## Related projects
The following projects are using this library:
* [PSIH & PMSIpilot](http://www.psih.fr/en/),
PSIH is the leading French integrator of business intelligence solutions for
the healthcare sector,
* [PHP Telegram Bot](https://github.com/akalongman/php-telegram-bot/),
Telegram bot based on the official Telegram Bot API.