Signum

Evaluate the signum function of a complex number.

Usage

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

csignum( [out,] re, im )

Evaluates the signum function of a `complex` number comprised of a real component `re` and an imaginary component `im`.

``````var v = csignum( -4.2, 5.5 );
// returns [ -0.6069136033622302, 0.79476781392673 ]

v = csignum( 0.0, 0.0 );
// returns [ 0.0, 0.0 ]

v = csignum( NaN, NaN );
// returns [ NaN, NaN ]
``````

By default, the function returns real and imaginary components as a two-element `array`. To avoid unnecessary memory allocation, the function supports providing an output (destination) object.

``````var Float64Array = require( '@stdlib/array/float64' );

var out = new Float64Array( 2 );

var v = csignum( out, -4.2, 5.5 );
// returns <Float64Array>[ -0.6069136033622302, 0.79476781392673 ]

var bool = ( v === out );
// returns true
``````

Examples

``````var Complex128 = require( '@stdlib/complex/float64' );
var randu = require( '@stdlib/random/base/randu' );
var real = require( '@stdlib/complex/real' );
var imag = require( '@stdlib/complex/imag' );
var csignum = require( '@stdlib/math/base/special/csignum' );

var re;
var im;
var z;
var o;
var w;
var i;

for ( i = 0; i < 100; i++ ) {
re = ( randu()*100.0 ) - 50.0;
im = ( randu()*100.0 ) - 50.0;
z = new Complex128( re, im );
o = csignum( real(z), imag(z) );
w = new Complex128( o[ 0 ], o[ 1 ] );
console.log( 'signum(%s) = %s', z.toString(), w.toString() );
}
``````