Words

Split a double-precision floating-point number into a higher order word and a lower order word.

Usage

var toWords = require( '@stdlib/number/float64/base/to-words' );

toWords( x )

Splits a double-precision floating-point number into a higher order word (unsigned 32-bit integer) and a lower order word (unsigned 32-bit integer).

var w = toWords( 3.14e201 );
// returns [ 1774486211, 2479577218 ]

By default, the function returns an array containing two elements: a higher order word and a lower order word. The lower order word contains the less significant bits, while the higher order word contains the more significant bits and includes the exponent and sign.

var w = toWords( 3.14e201 );
// returns [ 1774486211, 2479577218 ]

var high = w[ 0 ];
// returns 1774486211

var low = w[ 1 ];
// returns 2479577218

toWords.assign( x, out, stride, offset )

Splits a double-precision floating-point number into a higher order word (unsigned 32-bit integer) and a lower order word (unsigned 32-bit integer) and assigns results to a provided output array.

var Uint32Array = require( '@stdlib/array/uint32' );

var out = new Uint32Array( 2 );

var w = toWords.assign( 3.14e201, out, 1, 0 );
// returns <Uint32Array>[ 1774486211, 2479577218 ]

var bool = ( w === out );
// returns true

Examples

var floor = require( '@stdlib/math/base/special/floor' );
var randu = require( '@stdlib/random/base/randu' );
var pow = require( '@stdlib/math/base/special/pow' );
var toWords = require( '@stdlib/number/float64/base/to-words' );

var frac;
var exp;
var w;
var x;
var i;

// Generate random numbers and split into words...
for ( i = 0; i < 100; i++ ) {
    frac = randu() * 10.0;
    exp = -floor( randu()*324.0 );
    x = frac * pow( 10.0, exp );
    w = toWords( x );
    console.log( 'x: %d. higher: %d. lower: %d.', x, w[ 0 ], w[ 1 ] );
}

C APIs

Usage

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

stdlib_base_float64_to_words( x, *high, *low )

Splits a double-precision floating-point number into a higher order word and a lower order word.

#include <stdint.h>

uint32_t high;
uint32_t low;

stdlib_base_float64_to_words( 3.14, &high, &low );

The function accepts the following arguments:

  • x: [in] double input value.
  • high: [out] uint32_t* destination for higher order word.
  • low: [out] uint32_t* destination for lower order word.
void stdlib_base_float64_to_words( const double x, uint32_t *high, uint32_t *low );

stdlib_base_float64_words_t

An opaque type definition for a union for converting between a double-precision floating-point number and two unsigned 32-bit integers.

#include <stdint.h>

stdlib_base_float64_words_t w;

// Assign a double-precision floating-point number:
w.value = 3.14;

// Extract the high and low words:
uint32_t high = w.words.high;
uint32_t low = w.words.low;

The union has the following members:

  • value: double double-precision floating-point number.

  • words: struct struct having the following members:

    • high: uint32_t higher order word.
    • low: uint32_t lower order word.

Examples

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

int main( void ) {
    double x[] = { 3.14, -3.14, 0.0, 0.0/0.0 };

    uint32_t high;
    uint32_t low;
    int i;
    for ( i = 0; i < 4; i++ ) {
        stdlib_base_float64_to_words( x[ i ], &high, &low );
        printf( "%lf => high: %u, low: %u\n", x[ i ], high, low );
    }
}

See Also

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