time-to-botec/js/node_modules/@stdlib/stats/incr/sumabs2/README.md

incrsumabs2

Compute a sum of squared absolute values incrementally.

The sum of squared absolute values is defined as

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() );