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] floatinput value.
float stdlib_base_signumf( const float x );
Examples
#include "stdlib/math/base/special/signumf.h"
#include <stdio.h>
int main( void ) {
const 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 );
}
}