stats_dens_normal

(PECL stats >= 1.0.0)

stats_dens_normal — Probability density function of the normal distribution

说明

float stats_dens_normal ( float $x , float $ave , float $stdev )

Returns the probability density at x, where the random variable follows the normal distribution of which the mean is ave and the standard deviation is stdev.

参数

x: The value at which the probability density is calculated
ave: The mean of the distribution
stdev: The standard deviation of the distribution

返回值

The probability density at x or FALSE for failure.

User Contributed Notes

Anonymous 11-Aug-2009 01:12


There's a way to try it out:



<?php

...

echo"<pre>\n";

for($x=-2;$x<=2;$x+=0.1){

  echo"$i; ".stats_dens_normal($x,1,1)."\n";

}

echo"</pre>\n";

?>



Observe the result (to determine yourself), or

save it as "stats_dens_normal.csv",

load it into Open Office and make a graph of it

Anonymous 28-Feb-2009 11:37


I'm not certain that I've figured this one out correctly but it should return the value of a (Gaussian) normal distribution of the given properties at the given location.

$x - the X-Value to request

$ave - the 'expected value' (i.e. location of the peak) for the distribution. For most uses this will just be 0.

$stdev - the standard deviation of the distribution. For most uses this will be 1.