incrsumabs

Compute a sum of absolute values incrementally.

The sum of absolute values is defined as

s equals sigma-summation Underscript i equals 0 Overscript n minus 1 Endscripts StartAbsoluteValue x Subscript i Baseline EndAbsoluteValue

Usage

var incrsumabs = require( '@stdlib/stats/incr/sumabs' );

incrsumabs()

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

var accumulator = incrsumabs();

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 = incrsumabs();

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

sum = accumulator( -1.0 );
// returns 3.0

sum = accumulator( -3.0 );
// returns 6.0

sum = accumulator();
// returns 6.0

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 incrsumabs = require( '@stdlib/stats/incr/sumabs' );

var accumulator;
var v;
var i;

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

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