README.md

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 uniform = require( '@stdlib/random/array/uniform' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var copysign = require( '@stdlib/math/base/special/copysign' );

var opts = {
    'dtype': 'float64'
};
var x = uniform( 100, -50.0, 50.0, opts );
var y = uniform( 100, -5.0, 5.0, opts );

// Generate random double-precision floating-point numbers `x` and `y` and copy the sign of `y` to `x`...
logEachMap( 'x: %0.4f, y: %0.4f => %0.4f', x, y, copysign );

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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 );
    }
}

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See Also

• @stdlib/math/base/special/flipsign: return a double-precision floating-point number with the magnitude of x and the sign of x*y.