Signum

Signum function.

The signum function is defined as

for any real number x.

Usage

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


signumf( x )

Evaluates the signum function for a single-precision floating-point number.

var sign = signumf( -5.0 );
// returns -1

sign = signumf( 5.0 );
// returns 1

sign = signumf( -0.0 );
// returns -0

sign = signumf( 0.0 );
// returns 0

sign = signumf( NaN );
// returns NaN


Notes

Table of results:

ValueSign
x > 0+1
x < 0-1
00
-0-0
NaNNaN

Examples

var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var signumf = require( '@stdlib/math/base/special/signumf' );

var sign;
var x;
var i;

for ( i = 0; i < 100; i++ ) {
x = round( randu()*100.0 ) - 50.0;
sign = signumf( x );
console.log( 'signum(%d) = %d', x, sign );
}


C APIs

Usage

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


stdlib_base_signumf( x )

Evaluates the signum function for a single-precision floating-point number.

float y = stdlib_base_signumf( -9.0f );
// returns -1.0f


The function accepts the following arguments:

• x: [in] float input value.
float stdlib_base_signumf( const float x );


Examples

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

int main() {
float x[] = { 3.14f, -3.14f, 0.0f, 0.0f/0.0f };

float y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_signumf( x[ i ] );
printf( "signum(%f) = %f\n", x[ i ], y );
}
}