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Installing and configuring PHP Math Functions

In this page, we will discuss installing and configuring PHP math functions.

Requirements

PHP Math functions do not require any external library files.

Installation

Since PHP Math functions are part of the PHP core, they don't require any installation.

Runtime Configuration

You don't need to add any directive in php.ini for running PHP Math functions.

Resource Types

PHP Math functions have no defined resource types defined.

Predefined constants

In the following table, we have given a list of constants which are part of the PHP core.

Math constants
Constant Value Description Availability
M_PI 3.14159265358979323846 Pi  
M_E 2.7182818284590452354 e  
M_LOG2E 1.4426950408889634074 log_2 e  
M_LOG10E 0.43429448190325182765 log_10 e  
M_LN2 0.69314718055994530942 log_e 2  
M_LN10 2.30258509299404568402 log_e 10  
M_PI_2 1.57079632679489661923 pi/2  
M_PI_4 0.78539816339744830962 pi/4  
M_1_PI 0.31830988618379067154 1/pi  
M_2_PI 0.63661977236758134308 2/pi  
M_SQRTPI 1.77245385090551602729 sqrt(pi) PHP 5.2.0
M_2_SQRTPI 1.12837916709551257390 2/sqrt(pi)  
M_SQRT2 1.41421356237309504880 sqrt(2)  
M_SQRT3 1.73205080756887729352 sqrt(3) PHP 5.2.0
M_SQRT1_2 0.70710678118654752440 1/sqrt(2)  
M_LNPI 1.14472988584940017414 log_e(pi) PHP 5.2.0
M_EULER 0.57721566490153286061 Euler constant PHP 5.2.0
PHP_ROUND_HALF_UP 1 Round halves up PHP 5.3.0
PHP_ROUND_HALF_DOWN 2 Round halves down PHP 5.3.0
PHP_ROUND_HALF_EVEN 3 Round halves to even numbers PHP 5.3.0
PHP_ROUND_HALF_ODD 4 Round halves to odd numbers PHP 5.3.0
NAN NAN (as a float) Not A Number  
INF INF (as a float) The infinite  

See also

PHP Function Reference

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC