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

r s q r t f left-parenthesis x right-parenthesis equals StartFraction 1 Over StartRoot x EndRoot EndFraction

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 ) );
}

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() {
    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 );
    }
}