test.js

'use strict';

// MODULES //

var tape = require( 'tape' );
var PINF = require( '@stdlib/math/constants/float32-pinf' );
var NINF = require( '@stdlib/math/constants/float32-ninf' );
var randu = require( '@stdlib/math/base/random/randu' );
var round = require( '@stdlib/math/base/special/round' );
var pow = require( '@stdlib/math/base/special/pow' );
var toFloat32 = require( '@stdlib/math/base/utils/float64-to-float32' );
var bits = require( '@stdlib/math/base/utils/float32-to-binary-string' );
var significandf = require( './../lib' );


// TESTS //

tape( 'main export is a function', function test( t ) {
	t.ok( true, __filename );
	t.equal( typeof significandf, 'function', 'main export is a function' );
	t.end();
});

tape( 'the function returns a number', function test( t ) {
	t.equal( typeof significandf( toFloat32( 3.14e30 ) ), 'number', 'returns a number' );
	t.end();
});

tape( 'the function returns an integer corresponding to the significand of a single-precision floating-point number', function test( t ) {
	var expected;
	var actual;
	var sign;
	var frac;
	var exp;
	var x;
	var b;
	var i;

	for ( i = 0; i < 5000; i++ ) {
		if ( randu() < 0.5 ) {
			sign = -1.0;
		} else {
			sign = 1.0;
		}
		frac = randu() * 10.0;
		exp = round( randu()*44.0 ) - 22;
		x = sign * frac * pow( 10.0, exp );
		x = toFloat32( x );

		b = bits( x );
		expected = parseInt( b.substring( 9 ), 2 );

		actual = significandf( x );
		t.equal( actual, expected, 'returns the significand for ' + x );
	}
	t.end();
});

tape( 'the function returns the significand for `+-0`', function test( t ) {
	t.equal( significandf( 0.0 ), 0, 'returns 0' );
	t.equal( significandf( -0.0 ), 0, 'returns 0' );
	t.end();
});

tape( 'the function returns the significand for `+infinity`', function test( t ) {
	t.equal( significandf( PINF ), 0, 'returns 0' );
	t.end();
});

tape( 'the function returns the significand for `-infinity`', function test( t ) {
	t.equal( significandf( NINF ), 0, 'returns 0' );
	t.end();
});

tape( 'the function returns the significand for `NaN`', function test( t ) {
	t.equal( significandf( NaN ), 4194304, 'returns int corresponding to bit sequence 10000000000000000000000' );
	t.end();
});

tape( 'the function returns the significand for subnormals', function test( t ) {
	var x = toFloat32( 3.14e-42 );
	var s = parseInt( bits( x ).substring( 9 ), 2 );
	t.equal( significandf( x ), s, 'returns the significand for ' + x );
	t.end();
});