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

# meanandstddev

Return mean and standard deviation of array

## Declaration

Source position: line 0

 procedure meanandstddev( const data: array of Extended; var mean: float; var stddev: float );procedure meanandstddev( const data: PExtended; const N: LongInt; var mean: float; var stddev: float );

## Description

meanandstddev calculates the mean and standard deviation of data and returns the result in mean and stddev, respectively. Stddev is zero if there is only one value. The second form accepts a pointer to an array of N values.

## Errors

None.

 mean Return mean value of array sum Return sum of values sumofsquares Return sum of squares of values momentskewkurtosis Return 4 first moments of distribution

## Example

```Program Example28;

{ Program to demonstrate the Meanandstddev function. }

Uses math;

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

Var
I : Integer;
ExArray : TExArray;
Mean,stddev : Extended;

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