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Set High Word

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

Installation

npm install @stdlib/number-float64-base-set-high-word

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var setHighWord = require( '@stdlib/number-float64-base-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/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/random-base-randu' );
var MAX_UINT32 = require( '@stdlib/constants-uint32-max' );
var setHighWord = require( '@stdlib/number-float64-base-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 );
}

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C APIs

Usage

#include "stdlib/number/float64/base/set_high_word.h"

stdlib_base_float64_set_high_word( high, *x )

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

#include <stdint.h>

uint32_t high = 1074339512;
double x = 0.0;

stdlib_base_float64_set_high_word( high, &x );

The function accepts the following arguments:

• high: [in] uint32_t higher order word.
• x: [in-out] double* reference to (and destination for) a double-precision floating-point number.

void stdlib_base_float64_set_high_word( const uint32_t high, double *x );

Examples

#include "stdlib/number/float64/base/set_high_word.h"
#include <stdint.h>
#include <stdio.h>

int main( void ) {
    uint32_t high[] = { 1074339512, 1074339513, 1074339514, 1074339515 };
    double x = 3.14;

    int i;
    for ( i = 0; i < 4; i++ ) {
        stdlib_base_float64_set_high_word( high[ i ], &x );
        printf( "high: %u => %lf\n", high[ i ], x );
    }
}

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See Also

• @stdlib/number-float64/base/get-high-word: return an unsigned 32-bit integer corresponding to the more significant 32 bits of a double-precision floating-point number.
• @stdlib/number-float64/base/set-low-word: set the less significant 32 bits of a double-precision floating-point number.

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.