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.
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 ] )
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)
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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Thanks for reading and bye for now.