harmonic-mean ( seq -- x )
Statistics

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Vocabulary
math.statistics

Inputs

seq	a sequence

Outputs

x	a non-negative real number

Word description
Computes the harmonic mean of the elements in seq. The harmonic mean is appropriate when the average of rates is desired.

Notes
Positive reals only.

Examples

USING: math.statistics prettyprint ; { 1 2 3 } harmonic-mean .
1+7/11

Errors
Throws a signal-error. (divide by zero) if the sequence is empty.

Definition

USING: kernel math sequences ;

IN: math.statistics

: harmonic-mean ( seq -- x )
    [ [ recip ] map-sum ] [ length swap / ] bi ; inline