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Reference for unit 'math' (#rtl)

popnstddev

Return population variance

Declaration

Source position: math.pp line 483

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.

See also

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.