stats_dens_normal

(PECL stats >= 1.0.0)

stats_dens_normal — Probability density function of the normal distribution

说明

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

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.

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User Contributed Notes 3 notes

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Hector ¶

4 years ago

This functions will be the equivalent for "DISTR.NORM.N" on excel, like an other user said it's for Gaussian normal distribution.

$x as value to analyze
$ave as average 
$stdev as deviation

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Anonymous ¶

14 years ago

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.

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-8

Anonymous ¶

14 years ago

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

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