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

# PopnVariance

Return population variance

## Declaration

Source position: math.pp line 533

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

## Description

Popnvariance 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.

## See also

popnstddev |  | Return Population standard deviation
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 Example36;

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

    Uses math;

    Var
      I : Integer;
      ExArray : Array[1..100] of Float;

    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. var.     : ',PopnVariance(ExArray):8:4);
      Writeln('Pop. var. (b) : ',PopnVariance(@ExArray[1],100):8:4);
    end.