npm package: @stdlib/number-float64-base-set-high-word
Description: Set the more significant 32 bits of a double-precision floating-point number.
Author: The Stdlib Authors
Latest version: 0.2.3

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# Set High Word

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Set the more significant 32 bits of a [double-precision floating-point number][ieee754].

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

```javascript
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][ieee754] `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`.

```javascript
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
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
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 );
}
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

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<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#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.

```c
#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.

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

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#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 );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/number-float64/base/get-high-word`][@stdlib/number/float64/base/get-high-word]</span><span class="delimiter">: </span><span class="description">return an unsigned 32-bit integer corresponding to the more significant 32 bits of a double-precision floating-point number.</span>
-   <span class="package-name">[`@stdlib/number-float64/base/set-low-word`][@stdlib/number/float64/base/set-low-word]</span><span class="delimiter">: </span><span class="description">set the less significant 32 bits of a double-precision floating-point number.</span>

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985

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