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

# TotalVariance

Return total variance of values

## Declaration

Source position: math.pp line 526

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

## Description

TotalVariance returns the total variance of the values in the data array. It returns zero if there is only one value.

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

## Errors

None.

## See also

variance |  | Return variance of values
stddev |  | Return standard deviation of data
mean |  | Return mean value of array

## Example

    Program Example49;

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

    Uses math;

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

    Var
      I : Integer;
      ExArray : TExArray;
      TV : float;

    begin
      Randomize;
      for I:=1 to 100 do
        ExArray[i]:=(Random-Random)*100;
      TV:=TotalVariance(ExArray);
      Writeln('Total variance     : ',TV:8:4);
      TV:=TotalVariance(@ExArray[1],100);
      Writeln('Total Variance (b) : ',TV:8:4);
    end.