@stdlib/math-base-special-copysign NPM

copysign

$NPM version$ $Build Status$ $Coverage Status$

Return a double-precision floating-point number with the magnitude of x and the sign of y.

Installation

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

Usage

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

copysign( x, y )

Returns a double-precision floating-point number with the magnitude of x and the sign of y.

var z = copysign( -3.14, 10.0 );
// returns 3.14

z = copysign( 3.14, -1.0 );
// returns -3.14

z = copysign( 1.0, -0.0 );
// returns -1.0

z = copysign( -3.14, -0.0 );
// returns -3.14

z = copysign( -0.0, 1.0 );
// returns 0.0

Notes

According to the IEEE754 standard, a NaN has a biased exponent equal to 2047, a significand greater than 0, and a sign bit equal to either 1 or 0. In which case, NaN may not correspond to just one but many binary representations. Accordingly, care should be taken to ensure that y is not NaN; otherwise, behavior may be indeterminate.

Examples

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

var x;
var y;
var z;
var i;

// Generate random double-precision floating-point numbers `x` and `y` and copy the sign of `y` to `x`...
for ( i = 0; i < 100; i++ ) {
    x = (randu()*100.0) - 50.0;
    y = (randu()*10.0) - 5.0;
    z = copysign( x, y );
    console.log( 'x: %d, y: %d => %d', x, y, z );
}

C APIs

Usage

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

stdlib_base_copysign( x, y )

Returns a double-precision floating-point number with the magnitude of x and the sign of y.

double v = stdlib_base_copysign( -3.14, 10.0 );
// returns 3.14

double v = stdlib_base_copysign( 3.14, -1.0 );
// returns -3.14

The function accepts the following arguments:

x: [in] double number from which to derive a magnitude.
y: [in] double number from which to derive a sign.

double stdlib_base_copysign( const double x, const double y );

Examples

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

int main( void ) {
    const double x[] = { 3.14, -3.14, 0.0, 0.0/0.0 };

    double y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_copysign( x[ i ], -3.0 );
        printf( "copysign(%lf, %lf) = %lf\n", x[ i ], -3.0, 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.