PHP | stats_dens_t() Function

PHP stats_dens_t() 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_dens_t() Function.

The built-in stats_dens_t() function is the probability density function of t distribution.

Syntax

Following below is the syntax to use this function -

float stats_dens_t( float $x, float $dfr )


Parameter Details

Sr.NoParameterDescription
1

x

The value at which the probability density is calculated

2

dfr

The degree of freedom of the distribution


Return Value

This built-in function returns the probability density at x, where the random variable can follow the t distribution of which the degree of freedom is dfr, else 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 probability density at x -

<?php
   // check foreach x
   foreach (range(-1, 1, 0.5) as $x) {
      var_dump(round(stats_dens_t($x, 1), 6));
      echo "<br>";
   }
?>

Output

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

float(0.159155)
float(0.254648)
float(0.31831)
float(0.254648)
float(0.159155)

Example2

The following example below computes the probability density for each dfr -

<?php
   // check foreach dfr
   foreach (range(0.5, 2, 0.5) as $dfr) {
      var_dump(round(stats_dens_t(0, $dfr), 6));
      echo "<br>";
   }
?>

Output

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

float(0.269676)
float(0.31831)
float(0.340735)
float(0.353553)

Example3

The following below is an error case. In the below example, we have passed dfr == 0. A warning is shown in logs -

<?php
   // error cases
   var_dump(stats_dens_t(1, 0));   // dfr == 0
?>

Output

The above code will produce the following result and a warning in logs PHP Warning: stats_dens_t(): dfr == 0.0

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 PHP stats_dens_uniform() Function.

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