signbit

Return a boolean indicating if the sign bit for a double-precision floating-point number is on (true) or off (false).

Installation

npm install @stdlib/number-float64-base-signbit

Usage

var signbit = require( '@stdlib/number-float64-base-signbit' );

signbit( x )

Returns a boolean indicating if the sign bit for a double-precision floating-point number is on (true) or off (false).

var bool = signbit( 4.0 );
// returns false

bool = signbit( -9.14e-307 );
// returns true

bool = signbit( 0.0 );
// returns false

bool = signbit( -0.0 );
// returns true

Examples

var randu = require( '@stdlib/random-base-randu' );
var signbit = require( '@stdlib/number-float64-base-signbit' );

var sign;
var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = ( randu()*100.0 ) - 50.0;
    sign = signbit( x );
    sign = ( sign ) ? 'true' : 'false';
    console.log( 'x: %d. signbit: %s.', x, sign );
}

C APIs

Usage

#include "stdlib/number/float64/base/signbit.h"

stdlib_base_float64_signbit( x )

Returns an integer indicating whether the sign bit for a double-precision floating-point number is on (1) or off (0).

#include <stdint.h>

int8_t out = stdlib_base_float64_signbit( 3.14 );

The function accepts the following arguments:

• x: [in] double input value.

int8_t stdlib_base_float64_signbit( const double x );

Examples

#include "stdlib/number/float64/base/signbit.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>

int main( void ) {
    double x[] = { 3.14, -3.14, 0.0, -0.0, 4.0, 1.0, -1.0, 1.0e308, -1.0e308 };

    int8_t out;
    int i;
    for ( i = 0; i < 9; i++ ) {
        stdlib_base_float64_signbit( x[ i ], &out );
        printf( "%lf => signbit: %" PRId8 "\n", x[ i ], out );
    }
}

See Also

• @stdlib/number-float32/base/signbit: return a boolean indicating if the sign bit for a single-precision floating-point number is on (true) or off (false).

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 © 2016-2024. The Stdlib Authors.