@stdlib/stats-incr-sum

Compute a sum incrementally.

Usage no npm install needed!

<script type="module">
  import stdlibStatsIncrSum from 'https://cdn.skypack.dev/@stdlib/stats-incr-sum';
</script>

README

incrsum

NPM version Build Status Coverage Status

Compute a sum incrementally.

The sum is defined as

Equation for the sum.

Installation

npm install @stdlib/stats-incr-sum

Usage

var incrsum = require( '@stdlib/stats-incr-sum' );

incrsum()

Returns an accumulator function which incrementally computes a sum.

var accumulator = incrsum();

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 = incrsum();

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 incrsum = require( '@stdlib/stats-incr-sum' );

var accumulator;
var v;
var i;

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

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

References

  • Klein, Andreas. 2005. "A Generalized Kahan-Babuška-Summation-Algorithm." Computing 76 (3): 279–93. doi:10.1007/s00607-005-0139-x.

See Also

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.

Community

Chat

License

See LICENSE.

Copyright

Copyright © 2016-2022. The Stdlib Authors.