# HARMEAN Function

Returns the harmonic mean.

 Category: Descriptive Statistics

## Syntax

HARMEAN(argument<,argument,…> )

### Required Argument

#### argument

is a nonnegative numeric constant, variable, or expression.

 Tip The argument list can consist of a variable list, which is preceded by OF.

## Details

If any argument is negative, then the result is a missing value. A message appears in the log that the negative argument is invalid, and _ERROR_ is set to 1. If all the arguments are missing values, then the result is a missing value. Otherwise, the result is the harmonic mean of the nonmissing values.
If any argument is zero, then the harmonic mean is zero. Otherwise, the harmonic mean is the reciprocal of the arithmetic mean of the reciprocals of the values.
Let $equation$ be the number of arguments with nonmissing values, and let $equation$ be the values of those arguments. The harmonic mean is
$equation$
Floating-point arithmetic often produces tiny numerical errors. Some computations that result in zero when exact arithmetic is used might result in a tiny nonzero value when floating-point arithmetic is used. Therefore, HARMEAN fuzzes the values of arguments that are approximately zero. When the value of one argument is extremely small relative to the largest argument, then the former argument is treated as zero. If you do not want SAS to fuzz the extremely small values, then use the HARMEANZ function.

## Comparisons

The MEAN function returns the arithmetic mean (average), and the GEOMEAN function returns the geometric mean, whereas the HARMEAN function returns the harmonic mean of the nonmissing values. Unlike HARMEANZ, HARMEAN fuzzes the values of the arguments that are approximately zero.

## Example

The following SAS statements produce these results.
SAS Statement
Result
`x1=harmean(1,2,4,4);`
`2`
`x2=harmean(.,4,12,24);`
`8`
`x3=harmean(of x1-x2);`
`3.2`