Decompose a double-precision floating-point number into integral and fractional parts.
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> Decompose a [double-precision floating-point number][ieee754] into integral and fractional parts.
``bash`
npm install @stdlib/math-base-special-modf
`javascript`
var modf = require( '@stdlib/math-base-special-modf' );
#### modf( x )
Decomposes a [double-precision floating-point number][ieee754] into integral and fractional parts, each having the same type and sign as x.
`javascript
var parts = modf( 3.14 );
// returns [ 3.0, 0.14000000000000012 ]
parts = modf( +0.0 );
// returns [ +0.0, +0.0 ]
parts = modf( -0.0 );
// returns [ -0.0, -0.0 ]
parts = modf( Infinity );
// returns [ Infinity, +0.0 ]
parts = modf( -Infinity );
// returns [ -Infinity, -0.0 ]
parts = modf( NaN );
// returns [ NaN, NaN ]
`
#### modf.assign( x, out, stride, offset )
Decomposes a [double-precision floating-point number][ieee754] into integral and fractional parts, each having the same type and sign as x, and assigns results to a provided output array.
`javascript
var Float64Array = require( '@stdlib/array-float64' );
var out = new Float64Array( 2 );
var parts = modf.assign( 3.14, out, 1, 0 );
// returns
var bool = ( parts === out );
// returns true
`
`javascript
var randu = require( '@stdlib/random-base-randu' );
var modf = require( '@stdlib/math-base-special-modf' );
var parts;
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*1000.0) - 500.0;
parts = modf( x );
console.log( 'modf(%d) => integral: %d. fraction: %d.', x, parts[ 0 ], parts[ 1 ] );
}
`
*
`c`
#include "stdlib/math/base/special/modf.h"
#### stdlib_base_modf( x, integral, frac )
Decomposes a [double-precision floating-point number][ieee754] into integral and fractional parts, each having the same type and sign as x.
`c
double integral;
double frac;
stdlib_base_modf( 4.0, &integral, &frac );
`
The function accepts the following arguments:
- x: [in] double input value.[out] double*
- integral: destination for the integral part.[out] double*
- frac: destination for the fractional part.
`c`
void stdlib_base_modf( const double x, double integral, double frac );
`c
#include "stdlib/math/base/special/modf.h"
#include
int main( void ) {
const double x[] = { 4.0, 0.0, -0.0, 1.0, -1.0, 3.14, -3.14, 1.0e308, -1.0e308, 1.0/0.0, -1.0/0.0, 0.0/0.0 };
double integral;
double frac;
int i;
for ( i = 0; i < 12; i++ ) {
stdlib_base_modf( x[ i ], &integral, &frac );
printf( "x: %lf => integral: %lf, frac: %lf\n", x[ i ], integral, frac );
}
}
`
*
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].
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---
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Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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