@stdlib/stats-incr-sumabs2 NPM

incrsumabs2

Compute a sum of squared absolute values incrementally.

The sum of squared absolute values is defined as

Installation

npm install @stdlib/stats-incr-sumabs2

Usage

var incrsumabs2 = require( '@stdlib/stats-incr-sumabs2' );

incrsumabs2()

Returns an accumulator function which incrementally computes a sum of squared absolute values.

var accumulator = incrsumabs2();

accumulator( [x] )

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

var accumulator = incrsumabs2();

var sum = accumulator( 2.0 );
// returns 4.0

sum = accumulator( -1.0 );
// returns 5.0

sum = accumulator( -3.0 );
// returns 14.0

sum = accumulator();
// returns 14.0

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.
For long running accumulations or accumulations of large numbers, care should be taken to prevent overflow.

Examples

var randu = require( '@stdlib/random-base-randu' );
var incrsumabs2 = require( '@stdlib/stats-incr-sumabs2' );

var accumulator;
var v;
var i;

// Initialize an accumulator:
accumulator = incrsumabs2();

// For each simulated datum, update the sum...
for ( i = 0; i < 100; i++ ) {
    v = ( randu()*100.0 ) - 50.0;
    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.