[Overview][Constants][Types][Classes][Procedures and functions][Index] Reference for unit 'Math' (#rtl)

# PopnStdDev

Return Population standard deviation

## Declaration

Source position: math.pp line 531

 function PopnStdDev( const data: array of Single ):Float;function PopnStdDev( const data: PSingle; const N: Integer ):Float;function PopnStdDev( const data: array of Double ):Float;function PopnStdDev( const data: PDouble; const N: Integer ):Float;function PopnStdDev( const data: array of Extended ):Float;function PopnStdDev( const data: PExtended; const N: Integer ):Float;

## Description

Popnstddev returns the square root of the population variance of the values in the Data array. It returns zero if there is only one value.

The second form of this function accepts a pointer to an array of N values.

## Errors

None.

 popnvariance Return population variance mean Return mean value of array meanandstddev Return mean and standard deviation of array stddev Return standard deviation of data momentskewkurtosis Return 4 first moments of distribution

## Example

```Program Example35;

{ Program to demonstrate the PopnStdDev function. }
{ @ should return typed pointer }
{\$T+}

Uses Math;

Type
TExArray = Array[1..100] of Float;

Var
I : Integer;
ExArray : TExArray;

begin
Randomize;
for I:=low(ExArray) to high(ExArray) do
ExArray[i]:=(Random-Random)*100;
Writeln('Max              : ',MaxValue(ExArray):8:4);
Writeln('Min              : ',MinValue(ExArray):8:4);
Writeln('Pop. stddev.     : ',PopnStdDev(ExArray):8:4);
Writeln('Pop. stddev. (b) : ',PopnStdDev(@ExArray[1],100):8:4);
end.
```