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

# TotalVariance

## Declaration

Source position: math.pp line 518

 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.

 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.
```