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Reciprocal Square Root

Compute the reciprocal of the principal square root of a single-precision floating-point number.

The reciprocal of the principal square root is defined as

$$\mathop{\mathrm{rsqrtf}}(x)=\frac{1}{\sqrt{x}}$$

Installation

npm install @stdlib/math-base-special-rsqrtf

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 rsqrtf = require( '@stdlib/math-base-special-rsqrtf' );

rsqrtf( x )

Computes the reciprocal (inverse) square root of a single-precision floating-point number.

var v = rsqrtf( 1.0 );
// returns 1.0

v = rsqrtf( 4.0 );
// returns 0.5

v = rsqrtf( 0.0 );
// returns Infinity

v = rsqrtf( NaN );
// returns NaN

v = rsqrtf( Infinity );
// returns 0.0

For negative numbers, the reciprocal square root is not defined.

var v = rsqrtf( -4.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var rsqrtf = require( '@stdlib/math-base-special-rsqrtf' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu() * 100.0 );
    console.log( 'rsqrt(%d) = %d', x, rsqrtf( x ) );
}

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C APIs

Usage

#include "stdlib/math/base/special/rsqrtf.h"

stdlib_base_rsqrtf( x )

Computes the reciprocal (inverse) square root of a single-precision floating-point number.

float y = stdlib_base_rsqrtf( 4.0 );
// returns 0.5

The function accepts the following arguments:

• x: [in] float input value.

float stdlib_base_rsqrtf( const float x );

Examples

#include "stdlib/math/base/special/rsqrtf.h"
#include <stdio.h>

int main( void ) {
    const float x[] = { 3.14f, 9.0f, 0.0f, 0.0f/0.0f };

    float y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_rsqrtf( x[ i ] );
        printf( "rsqrt(%f) = %f\n", x[ i ], y );
    }
}

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See Also

• @stdlib/math-base/special/rsqrt: compute the reciprocal square root of a double-precision floating-point number.
• @stdlib/math-base/special/sqrtf: compute the principal square root of a single-precision floating-point number.

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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.