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https://github.com/stdlib-js/math-iter-special-log

Create an iterator which computes the base `b` logarithm.
https://github.com/stdlib-js/math-iter-special-log

base function iterable iterate iterator javascript log logarithm math mathematics node node-js nodejs stdlib

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Create an iterator which computes the base `b` logarithm.

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README 

        



  

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# iterLog



[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] 



> Create an [iterator][mdn-iterator-protocol] which iteratively computes the base `b` [logarithm][@stdlib/math/base/special/log].



## Installation



```bash

npm install @stdlib/math-iter-special-log

```



Alternatively,



-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).

-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).

-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).



The [branches.md][branches-url] 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



```javascript

var iterLog = require( '@stdlib/math-iter-special-log' );

```



#### iterLog( x, b )



Returns an [iterator][mdn-iterator-protocol] which iteratively computes the base `b` [logarithm][@stdlib/math/base/special/log] of `x`.



```javascript

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



var x = array2iterator( [ 2.0, 2.0, 10.0 ] );

var y = array2iterator( [ 2.0, 6.0, 2.0 ] );



var it = iterLog( x, y );

// returns 



var r = it.next().value;

// returns 1.0



r = it.next().value;

// returns ~0.3869



r = it.next().value;

// returns ~3.3219



// ...

```



The returned [iterator][mdn-iterator-protocol] protocol-compliant object has the following properties:



-   **next**: function which returns an [iterator][mdn-iterator-protocol] protocol-compliant object containing the next iterated value (if one exists) assigned to a `value` property and a `done` property having a `boolean` value indicating whether the iterator is finished.

-   **return**: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object.



If provided a numeric value as an [`iterator`][mdn-iterator-protocol] argument, the value is broadcast as an **infinite** [iterator][mdn-iterator-protocol] which **always** returns the provided value.



```javascript

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



var x = array2iterator( [ 2.0, 6.0 ] );



var it = iterLog( x, 2.0 );

// returns 



var v = it.next().value;

// returns 1.0



v = it.next().value;

// returns ~2.58496



var bool = it.next().done;

// returns true

```



## Notes



-   For negative `b` or `x` iterated values, the returned [iterator][mdn-iterator-protocol] returns `NaN`.

-   If an iterated value is non-numeric (including `NaN`), the returned [iterator][mdn-iterator-protocol] returns `NaN`. If non-numeric iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles non-numeric values accordingly.

-   The length of the returned [iterator][mdn-iterator-protocol] is equal to the length of the shortest provided [iterator][mdn-iterator-protocol]. In other words, the returned [iterator][mdn-iterator-protocol] ends once **one** of the provided [iterators][mdn-iterator-protocol] ends.

-   If an environment supports `Symbol.iterator` **and** a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.



## Examples



```javascript

var uniform = require( '@stdlib/random-iter-uniform' );

var iterLog = require( '@stdlib/math-iter-special-log' );



// Create seeded iterators for generating pseudorandom numbers:

var x = uniform( 0.0, 100.0, {

    'seed': 1234,

    'iter': 10

});



var y = uniform( 0.0, 10.0, {

    'seed': 4567,

    'iter': 10

});



// Create an iterator which consumes the pseudorandom number iterators:

var it = iterLog( x, y );



// Perform manual iteration...

var r;

while ( true ) {

    r = it.next();

    if ( r.done ) {

        break;

    }

    console.log( r.value );

}

```



* * *



## See Also



-   [`@stdlib/math-base/special/log`][@stdlib/math/base/special/log]: base `b` logarithm.

-   [`@stdlib/math-iter/special/log10`][@stdlib/math/iter/special/log10]: create an iterator which evaluates the common logarithm (logarithm with base 10) for each iterated value.

-   [`@stdlib/math-iter/special/log1p`][@stdlib/math/iter/special/log1p]: create an iterator which evaluates the natural logarithm of 1+x for each iterated value.

-   [`@stdlib/math-iter/special/log2`][@stdlib/math/iter/special/log2]: create an iterator which evaluates the binary logarithm for each iterated value.

-   [`@stdlib/math-iter/special/pow`][@stdlib/math/iter/special/pow]: create an iterator which evaluates the exponential function.



* * *



## Notice



This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].



#### Community



[![Chat][chat-image]][chat-url]



---



## License



See [LICENSE][stdlib-license].



## Copyright



Copyright © 2016-2024. The Stdlib [Authors][stdlib-authors].



[npm-image]: http://img.shields.io/npm/v/@stdlib/math-iter-special-log.svg

[npm-url]: https://npmjs.org/package/@stdlib/math-iter-special-log



[test-image]: https://github.com/stdlib-js/math-iter-special-log/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/math-iter-special-log/actions/workflows/test.yml?query=branch:main



[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/math-iter-special-log/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/math-iter-special-log?branch=main



[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg

[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im



[stdlib]: https://github.com/stdlib-js/stdlib



[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors



[umd]: https://github.com/umdjs/umd

[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules



[deno-url]: https://github.com/stdlib-js/math-iter-special-log/tree/deno

[deno-readme]: https://github.com/stdlib-js/math-iter-special-log/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/math-iter-special-log/tree/umd

[umd-readme]: https://github.com/stdlib-js/math-iter-special-log/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/math-iter-special-log/tree/esm

[esm-readme]: https://github.com/stdlib-js/math-iter-special-log/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/math-iter-special-log/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-iter-special-log/main/LICENSE



[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol



[@stdlib/math/base/special/log]: https://github.com/stdlib-js/math-base-special-log



[@stdlib/math/iter/special/log10]: https://github.com/stdlib-js/math-iter-special-log10



[@stdlib/math/iter/special/log1p]: https://github.com/stdlib-js/math-iter-special-log1p



[@stdlib/math/iter/special/log2]: https://github.com/stdlib-js/math-iter-special-log2



[@stdlib/math/iter/special/pow]: https://github.com/stdlib-js/math-iter-special-pow