@stdlib/stats-incr-hmean NPM

incrhmean

Compute a harmonic mean incrementally.

The harmonic mean of positive real numbers x_0, x_1, ..., x_{n-1} is defined as

Installation

npm install @stdlib/stats-incr-hmean

Usage

var incrhmean = require( '@stdlib/stats-incr-hmean' );

incrhmean()

Returns an accumulator function which incrementally computes a harmonic mean.

var accumulator = incrhmean();

accumulator( [x] )

If provided an input value x, the accumulator function returns an updated harmonic mean. If not provided an input value x, the accumulator function returns the current harmonic mean.

var accumulator = incrhmean();

var v = accumulator( 2.0 );
// returns 2.0

v = accumulator( 1.0 );
// returns ~1.33

v = accumulator( 3.0 );
// returns ~1.64

v = accumulator();
// returns ~1.64

Notes

Input values are not type checked. If provided NaN or a value which, when used in computations, results in NaN, the accumulated value is NaN for all future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly before passing the value to the accumulator function.

Examples

var randu = require( '@stdlib/random-base-randu' );
var incrhmean = require( '@stdlib/stats-incr-hmean' );

var accumulator;
var v;
var i;

// Initialize an accumulator:
accumulator = incrhmean();

// For each simulated datum, update the harmonic mean...
for ( i = 0; i < 100; i++ ) {
    v = randu() * 100.0;
    accumulator( v );
}
console.log( accumulator() );

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.