time-to-botec/squiggle/node_modules/@stdlib/math/base/special/signumf/README.md

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:

Value	Sign
x > 0	+1
x < 0	-1
0	0
-0	-0
NaN	NaN

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 );
    }
}