## NAME

average -- compute the average and standard deviation

## USAGE

`average option`

## PARAMETERS

- option
- Chosen from "add", "subtract" or "new_sample", in which case the numbers averaged are those in STDIN. If no argument is given on the command line, "new_sample" is assumed.

## DESCRIPTION

Task *average*
computes the average and standard deviation of a list
of numbers. Numeric input is read from STDIN with one number per line.
The mean, sigma and number of samples are written to the standard
output.

By default, the sample is taken to be
the set of numbers in the standard input when *average*
is run.
Additional points can be added to or deleted from the sample by rerunning
*average*
with **option**
equal to one of the following:

add -- add points to the sample, recalculate mean and sigma sub -- subtract points from the sample

The sample is reinitialized by setting **option**
= "new_sample".

## EXAMPLES

Run *average*
on the list of numbers in file "numbers".

cl> type numbers | average

Add in to the sample the list of numbers in file "numbers.2".

cl> average add < numbers.2