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itercuprod

Create an iterator which iteratively computes a cumulative product.

The cumulative product is defined as

$$\begin{align*} p_0 &= x_0 \\ p_1 &= x_1 \cdot p_0 \\ p_2 &= x_2 \cdot p_1 \\ p_n &= x_n \cdot p_{n-1} = x_n \cdot \prod_{i=0}^{n-1} x_i \end{align*}$$

Installation

npm install @stdlib/stats-iter-cuprod

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var itercuprod = require( '@stdlib/stats-iter-cuprod' );

itercuprod( iterator )

Returns an iterator which iteratively computes a cumulative product.

var array2iterator = require( '@stdlib/array-to-iterator' );

var arr = array2iterator( [ 2.0, 1.0, 3.0, -7.0, -5.0 ] );
var it = itercuprod( arr );

var p = it.next().value;
// returns 2.0

p = it.next().value;
// returns 2.0

p = it.next().value;
// returns 6.0

p = it.next().value;
// returns -42.0

p = it.next().value;
// returns 210.0

Notes

• If an iterated value is non-numeric (including NaN), the function returns NaN for all future iterations. If non-numeric iterated values are possible, you are advised to provide an iterator which type checks and handles non-numeric values accordingly.
• For iterators which can generate many values or which may output large numbers, care should be taken to prevent overflow.

Examples

var runif = require( '@stdlib/random-iter-uniform' );
var itercuprod = require( '@stdlib/stats-iter-cuprod' );

// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( -10.0, 10.0, {
    'seed': 1234,
    'iter': 100
});

// Create an iterator for iteratively computing a cumulative product:
var it = itercuprod( rand );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( typeof v.value === 'number' ) {
        console.log( 'prod: %d', v.value );
    }
    if ( v.done ) {
        break;
    }
}

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See Also

• @stdlib/stats-iter/cusum: create an iterator which iteratively computes a cumulative sum.
• @stdlib/stats-iter/prod: compute the product of all iterated values.

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.