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

Name Description
mean Return mean value of array
stddev Return standard deviation of data
variance Return variance of values

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.