PHP | stats_standard_deviation() Function

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_standard_deviation() function.

The built-in PHP stats_standard_deviation() function returns the standard deviation.

Syntax

Following below is the syntax to use this function -

float stats_standard_deviation( array $a [, bool $sample = false ] )

READ: PHP | stats_rand_gen_int() Function

Parameter Details

Sr.No	Parameter	Description
1	a	The array of data to find the standard deviation for. Note that all values of the array will be cast to float.
2	sample	Indicates if a represents a sample of the population; defaults to false.

Return Value

This function returns the standard deviation of the values in a on success, else it returns false on failure.

Errors/Exceptions

This built-in function raises an E_WARNING when there are fewer than 2 values in a.

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 below example computes the standard deviation of the values in an array -

<?php
   $a=array(4, 1, 7);
   $dev=stats_standard_deviation($a);
   var_dump(sprintf("%2.9f", $dev));
?>

Output

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

string(11) "2.449489743"

Example2

The following example below computes the standard deviation of the values in an array by passing $sample=1 -

<?php
   $a=array(5,7,8,10,10);
   var_dump(stats_standard_deviation($a,1));
?>

Output

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

float(2.1213203435596)

Example3

Following is an error case. In the following example below, we have passed an empty array. A warning is shown in logs -

<?php
   // error cases
   var_dump(stats_standard_deviation(array()));
?>

Output

The above code will produce the following result and a warning in logs PHP Warning: stats_standard_deviation(): The array has zero elements

bool(false)

READ: PHP | stats_skew() Function

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 built-in stats_stat_binomial_coef() Function.

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