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# isOdd [![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] > Test if a finite double-precision floating-point number is an odd number.
## Installation ```bash npm install @stdlib/math-base-assert-is-odd ```
## Usage ```javascript var isOdd = require( '@stdlib/math-base-assert-is-odd' ); ``` #### isOdd( x ) Tests if a **finite** double-precision floating-point number is an odd number. ```javascript var bool = isOdd( 5.0 ); // returns true bool = isOdd( -2.0 ); // returns false bool = isOdd( 0.0 ); // returns false bool = isOdd( NaN ); // returns false ```
## Notes - The function assumes a **finite** `number`. If provided positive or negative `infinity`, the function will return `true`, when, in fact, the result is undefined. If `x` can be `infinite`, wrap the implementation as follows: ```javascript function check( x ) { return ( x < Infinity && x > -Infinity && isOdd( x ) ); } var bool = check( Infinity ); // returns false bool = check( -Infinity ); // returns false ```
## Examples ```javascript var discreteUniform = require( '@stdlib/random-array-discrete-uniform' ); var logEachMap = require( '@stdlib/console-log-each-map' ); var isOdd = require( '@stdlib/math-base-assert-is-odd' ); var opts = { 'dtype': 'float64' }; var x = discreteUniform( 100, 0, 1000, opts ); function isOddWrapper( integer ) { return ( isOdd( integer ) ) ? 'odd' : 'not odd'; } logEachMap( '%d is %s', x, isOddWrapper ); ```
* * *
## C APIs
### Usage ```c #include "stdlib/math/base/assert/is_odd.h" ``` #### stdlib_base_is_odd( x ) Tests if a finite double-precision floating-point number is an odd number. ```c #include bool out = stdlib_base_is_odd( 1.0 ); // returns true out = stdlib_base_is_odd( 4.0 ); // returns false ``` The function accepts the following arguments: - **x**: `[in] double` input value. ```c bool stdlib_base_is_odd( const double x ); ```
### Examples ```c #include "stdlib/math/base/assert/is_odd.h" #include #include int main( void ) { const double x[] = { 5.0, -5.0, 3.14, -3.14, 0.0, 0.0/0.0 }; bool b; int i; for ( i = 0; i < 6; i++ ) { b = stdlib_base_is_odd( x[ i ] ); printf( "Value: %lf. Is Odd? %s.\n", x[ i ], ( b ) ? "True" : "False" ); } } ```
* * * ## See Also - [`@stdlib/math-base/assert/is-even`][@stdlib/math/base/assert/is-even]: test if a finite numeric value is an even number.
* * * ## 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 © 2016-2026. The Stdlib [Authors][stdlib-authors].
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