time-to-botec

README.md (4944B)

---

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 @license Apache-2.0
 
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 # Set Low Word
 
 > Set the less significant 32 bits of a [double-precision floating-point number][ieee754].
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var setLowWord = require( '@stdlib/number/float64/base/set-low-word' );
 ```
 
 #### setLowWord( x, low )
 
 Sets the less significant 32 bits (lower order word) of a [double-precision floating-point number][ieee754] `x` to a bit sequence represented by an unsigned 32-bit integer `low`. The returned `double` will have the same more significant 32 bits (higher order word) as `x`.
 
 ```javascript
 var low = 5 >>> 0; // => 00000000000000000000000000000101
 
 var x = 3.14e201; // => 0 11010011100 01001000001011000011 10010011110010110101100010000010
 
 var y = setLowWord( x, low ); // => 0 11010011100 01001000001011000011 00000000000000000000000000000101
 // returns 3.139998651394392e+201
 ```
 
 Setting the lower order bits of `NaN` or positive or negative `infinity` will return `NaN`, as `NaN` is [defined][ieee754] as a `double` whose exponent bit sequence is all ones and whose fraction can be any bit sequence **except** all zeros. Positive and negative `infinity` are [defined][ieee754] as `doubles` with an exponent bit sequence equal to all ones and a fraction equal to all zeros. Hence, changing the less significant bits of positive and negative `infinity` converts each value to `NaN`.
 
 ```javascript
 var PINF = require( '@stdlib/constants/float64/pinf' );
 var NINF = require( '@stdlib/constants/float64/ninf' );
 
 var low = 12345678;
 
 var y = setLowWord( PINF, low );
 // returns NaN
 
 y = setLowWord( NINF, low );
 // returns NaN
 
 y = setLowWord( NaN, low );
 // returns NaN
 ```
 
 </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 setLowWord = require( '@stdlib/number/float64/base/set-low-word' );
 
 var frac;
 var exp;
 var low;
 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 lower order word of `x` to generate new random numbers having the same higher order word...
 for ( i = 0; i < 100; i++ ) {
     low = round( randu()*MAX_UINT32 );
     y = setLowWord( x, low );
     console.log( 'x: %d. new low word: %d. y: %d.', x, low, y );
 }
 ```
 
 </section>
 
 <!-- /.examples -->
 
 <!-- C interface documentation. -->
 
 * * *
 
 <section class="c">
 
 ## C APIs
 
 <!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
 
 <section class="intro">
 
 </section>
 
 <!-- /.intro -->
 
 <!-- C usage documentation. -->
 
 <section class="usage">
 
 ### Usage
 
 ```c
 #include "stdlib/number/float64/base/set_low_word.h"
 ```
 
 #### stdlib_base_float64_set_low_word( low, \*x )
 
 Sets the less significant 32 bits of a double-precision floating-point number.
 
 ```c
 #include <stdint.h>
 
 uint32_t low = 1374389537;
 double x = 3.14;
 
 stdlib_base_float64_set_low_word( low, &x );
 ```
 
 The function accepts the following arguments:
 
 -   **low**: `[in] uint32_t` lower order word.
 -   **x**: `[in-out] double*` reference to (and destination for) a double-precision floating-point number.
 
 ```c
 void stdlib_base_float64_set_low_word( const uint32_t low, 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_low_word.h"
 #include <stdint.h>
 #include <stdio.h>
 
 int main() {
     uint32_t low[] = { 1374389535, 1374389545, 1374389555, 1374389565 };
     double x = 3.14;
 
     int i;
     for ( i = 0; i < 4; i++ ) {
         stdlib_base_float64_set_low_word( low[ i ], &x );
         printf( "low: %u => %.15lf\n", low[ i ], x );
     }
 }
 ```
 
 </section>
 
 <!-- /.examples -->
 
 </section>
 
 <!-- /.c -->
 
 <section class="links">
 
 [ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
 
 </section>
 
 <!-- /.links -->