ldexpf

Multiply a single-precision floating-point number by an integer power of two.

Installation

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

Usage

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

ldexpf( frac, exp )

Multiplies a single-precision floating-point number by an integer power of two (i.e., x = frac * 2^exp).

var x = ldexpf( 0.5, 3 ); // => 0.5 * 2^3 = 0.5 * 8
// returns 4.0

x = ldexpf( 4.0, -2 ); // => 4 * 2^(-2) = 4 * (1/4)
// returns 1.0

If frac equals positive or negative zero, NaN, or positive or negative infinity, the function returns a value equal to frac.

var x = ldexpf( 0.0, 20 );
// returns 0.0

x = ldexpf( -0.0, 39 );
// returns -0.0

x = ldexpf( NaN, -101 );
// returns NaN

x = ldexpf( Infinity, 11 );
// returns Infinity

x = ldexpf( -Infinity, -118 );
// returns -Infinity

Notes

• This function is the inverse of frexpf.

Examples

var linspace = require( '@stdlib/array-base-linspace' );
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var ldexpf = require( '@stdlib/math-base-special-ldexpf' );

var frac = linspace( 0.0, 100.0, 10 );
var exp = discreteUniform( 100, 0, 10 );

var i;
for ( i = 0; i < frac.length; i++ ) {
    console.log( 'ldexpf(%d,%d) = %d', frac[ i ], exp[ i ], ldexpf( frac[ i ], exp[ i ] ) );
}

C APIs

Usage

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

stdlib_base_ldexpf( frac, exp )

Multiplies a single-precision floating-point number by an integer power of two (i.e., x = frac * 2^exp).

float x = stdlib_base_ldexpf( 0.5f, 3 ); // => 0.5 * 2^3 = 0.5 * 8
// returns 4.0f

The function accepts the following arguments:

• frac: [in] float input value.
• exp: [in] int32_t integer power of two.

float stdlib_base_ldexpf( const float frac, const int32_t exp );

Examples

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

int main( void ) {
    float y;
    int i;

    const float frac[] = { 0.5f, 5.0f, 0.0f, 3.5f, 7.9f };
    const int32_t exp[] = { 3, -2, 20, 39, 14 };

    for ( i = 0; i < 5; i++ ) {
        y = stdlib_base_ldexpf( frac[ i ], exp[ i ] );
        printf( "ldexpf(%f, %d) = %f\n", frac[ i ], exp[ i ], y );
    }
}

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

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.