# PHP | stats_covariance() Function

March 22, 2021

Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP stats_covariance() Function.

The built-in PHP

The built-in PHP

*stats_covariance()*function computes the covariance of two data sets. Covariance in it's simple form is described as a measure which computes how much two random variable vary together.## Syntax

Following below is the syntax to use this function -

float stats_covariance( array $a, array $b )

## Parameter Details

Sr.No | Parameter | Description |
---|---|---|

1 | a | The first array |

2 | b | The second array |

## Return Value

This function returns the covariance of the arrays a and b, otherwise

*false*on failure.## Dependencies

This built-in function was first introduced in statistics extension (PHP version 4.0.0 and PEAR v1.4.0). In this tutorial guide, we used the latest release of stats-2.0.3 (PHP v7.0.0 or newer and PEAR version 1.4.0 or newer).

### Example1

The following example below computes the covariance of arrays a and b -

<?php $a = array(15, 16, 8, 6, 15, 12, 12, 18, 12, 20, 12, 14); $b = array(17.24, 15, 14.91, 4.5, 18, 6.29, 19.23, 18.69, 7.21, 42.06, 7.5, 8); var_dump(stats_covariance($a_1, $a_2)); ?>

#### Output

When the above code is executed, it will produce the following result -

float(25.460555555556)

### Example2

Following is an error case. In the following example below, we passed two arrays with different sizes. A warning is shown in logs.

<?php var_dump(stats_covariance(array(2,1), array(1))); //arrays not of same size ?>

#### Output

The above code will produce the following result and a warning in logs

*PHP Warning: stats_covariance(): The data set are not of the same size*.bool(false)

### Example3

Following is an error case. In the following example below, we passed two arrays with one of them having zero elements. Warning is displayed in logs.

<?php var_dump(stats_covariance(array(), array(0))); //first array with zero elements ?>

#### Output

The above code will produce the following result and a warning in logs

*PHP Warning: stats_covariance(): The first array has zero elements*.bool(false)

READ: PHP | Statistics Module

Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we are going to be discussing about the PHP

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*stats_dens_beta()*Function.Feel free to ask your questions where necessary and we will attend to them as soon as possible. If this tutorial was helpful to you, you can use the share button to share this tutorial.

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