itercuhmean

Create an iterator which iteratively computes a cumulative harmonic mean.

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

StartLayout 1st Row 1st Column upper H 2nd Column equals StartStartFraction n OverOver StartFraction 1 Over x 0 EndFraction plus StartFraction 1 Over x 1 EndFraction plus midline-horizontal-ellipsis plus StartFraction 1 Over x Subscript n minus 1 Baseline EndFraction EndEndFraction 2nd Row 1st Column Blank 2nd Column equals StartStartFraction n OverOver sigma-summation Underscript i equals 0 Overscript n minus 1 Endscripts StartFraction 1 Over x Subscript i Baseline EndFraction EndEndFraction 3rd Row 1st Column Blank 2nd Column equals left-parenthesis StartStartFraction sigma-summation Underscript i equals 0 Overscript n minus 1 Endscripts StartFraction 1 Over x Subscript i Baseline EndFraction OverOver n EndEndFraction right-parenthesis Superscript negative 1 EndLayout

Usage

var itercuhmean = require( '@stdlib/stats/iter/cuhmean' );

itercuhmean( iterator )

Returns an iterator which iteratively computes a cumulative harmonic mean.

var array2iterator = require( '@stdlib/array/to-iterator' );

var arr = array2iterator( [ 2.0, 1.0, 3.0, 7.0, 5.0 ] );
var it = itercuhmean( arr );

var v = it.next().value;
// returns 2.0

v = it.next().value;
// returns ~1.33

v = it.next().value;
// returns ~1.64

v = it.next().value;
// returns ~2.02

v = it.next().value;
// returns ~2.30

Notes

  • If an iterated value is non-numeric (including NaN), the function returns NaN for all future iterations. If non-numeric iterated values are possible, you are advised to provide an iterator which type checks and handles such values accordingly.

Examples

var runif = require( '@stdlib/random/iter/uniform' );
var itercuhmean = require( '@stdlib/stats/iter/cuhmean' );

// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( 0.0, 10.0, {
    'seed': 1234,
    'iter': 100
});

// Create an iterator for iteratively computing a cumulative harmonic mean:
var it = itercuhmean( rand );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( typeof v.value === 'number' ) {
        console.log( 'hmean: %d', v.value );
    }
    if ( v.done ) {
        break;
    }
}