copysign

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

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 );
    }
}