signbit

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

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 );
    }
}