@stdlib/stats-incr-sum
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    0.0.6 • Public • Published

    incrsum

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    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.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2022. The Stdlib Authors.

    Install

    npm i @stdlib/stats-incr-sum

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    stdlib.io

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    0.0.6

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