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.
User Contributed Notes 2 notes
up down 0 Anonymous ¶10 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.
$stdev - the standard deviation of the distribution. For most uses this will be 1.
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down
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Anonymous ¶9 years ago
There's a way to try it out:
<?php
...
echo"<pre>\n";
for($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
add a note
官方地址：https://www.php.net/manual/en/function.stats-dens-normal.php