Set High Word

Set the more significant 32 bits of a double-precision floating-point number.

Usage

var setHighWord = require( '@stdlib/math/base/utils/float64-set-high-word' );

setHighWord( x, high )

Sets the more significant 32 bits (higher order word) of a double-precision floating-point number x to a bit sequence represented by an unsigned 32-bit integer high. The returned double will have the same less significant 32 bits (lower order word) as x.

var high = 5 >>> 0; // => 0 00000000000 00000000000000000101

var y = setHighWord( 3.14e201, high ); //  => 0 00000000000 0000000000000000010110010011110010110101100010000010
// returns 1.18350528745e-313

var PINF = require( '@stdlib/math/constants/float64-pinf' ); //  => 0 11111111111 00000000000000000000 00000000000000000000000000000000

high = 1072693248 >>> 0; // => 0 01111111111 00000000000000000000

// Set the higher order bits of `+infinity` to return `1`:
y = setHighWord( PINF, high );  => 0 01111111111 0000000000000000000000000000000000000000000000000000
// returns 1.0

Examples

var pow = require( '@stdlib/math/base/special/pow' );
var round = require( '@stdlib/math/base/special/round' );
var randu = require( '@stdlib/math/base/random/randu' );
var MAX_UINT32 = require( '@stdlib/math/constants/uint32-max' );
var setHighWord = require( '@stdlib/math/base/utils/float64-set-high-word' );

var high;
var frac;
var exp;
var x;
var y;
var i;

// Generate a random double-precision floating-point number:
frac = randu() * 10.0;
exp = -round( randu() * 323.0 );
x = frac * pow( 10.0, exp );

// Replace the higher order word of `x` to generate new random numbers having the same lower order word...
for ( i = 0; i < 100; i++ ) {
    high = round( randu()*MAX_UINT32 );
    y = setHighWord( x, high );
    console.log( 'x: %d. new high word: %d. y: %d.', x, high, y );
}