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

# variance

Return variance of values

## Declaration

Source position: math.pp line 477

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

## Description

Variance returns the 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.

 totalvariance Return total varians of values stddev Return standard deviation of data mean Return mean value of array

## Example

```Program Example50;

{ Program to demonstrate the Variance function. }

Uses math;

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

begin
Randomize;
for I:=low(ExArray) to high(ExArray) do
ExArray[i]:=(Random-Random)*100;
V:=Variance(ExArray);
Writeln('Variance     : ',V:8:4);
V:=Variance(@ExArray[1],100);
Writeln('Variance (b) : ',V:8:4);
end.
```