PHP | stats_dens_gamma() 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_gamma() Function.

The built-in stats_dens_gamma() function in php is the probability density function of the gamma distribution.

Syntax

Following below is the syntax to use this function -

float stats_dens_gamma( float $x, float $shape, float $scale )

READ: PHP | stats_dens_beta() Function

Parameter Details

Sr.No	Parameter	Description
1	x	The value at which the probability density is calculated
2	shape	The shape parameter of the distribution
3	scale	The scale parameter of the distribution

Return Value

This built-in function returns the probability density at x, where the random variable can follow the gamma distribution of which the shape and scale parameters are shape and scale or 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 for each x -

<?php
   // check for each x
   foreach (range(0.5, 2, 0.5) as $x) {
      var_dump(round(stats_dens_gamma($x, 1, 1), 6));
      echo "<br>";
   }
?>

Output

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

float(0.606531)
float(0.367879)
float(0.22313)
float(0.135335)

Example2

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

<?php
   // check for each shape
   foreach (range(0.5, 2, 0.5) as $shape) {
      var_dump(round(stats_dens_gamma(1, $shape, 1), 6));
      echo "<br>";
   }
?>

Output

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

float(0.207554)
float(0.367879)
float(0.415107)
float(0.367879)

Example3

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

<?php
   // check for each scale
   foreach (range(0.5, 2, 0.5) as $scale) {
      var_dump(round(stats_dens_gamma(1, 1, $scale), 6));
      echo "<br>";
   }
?>

Output

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

float(0.270671)
float(0.367879)
float(0.342278)
float(0.303265)

Example4

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

<?php
   // error cases
   var_dump(stats_dens_gamma(1, 0)); // scale = 0
?>

Output

The above code will produce the following result and a warning in logs PHP Warning: stats_dens_gamma(): scale is 0.0

bool(false)

READ: PHP | stats_dens_f() 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 stats_dens_laplace() Function in PHP.

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