@stdlib/math-base-special-ldexp
Advanced tools
Multiply a double-precision floating-point number by an integer power of two.
@stdlib/math-base-special-ldexp is a specialized npm package that provides a function to multiply a number by an integer power of two. This is useful in various mathematical computations, particularly in floating-point arithmetic and scientific calculations.
Multiply a number by an integer power of two
This feature allows you to multiply a floating-point number by 2 raised to the power of an integer. In this example, 1.5 is multiplied by 2^3, resulting in 12.
const ldexp = require('@stdlib/math-base-special-ldexp');
const result = ldexp(1.5, 3);
console.log(result); // 12mathjs is a comprehensive math library for JavaScript and Node.js. It provides a wide range of mathematical functions, including basic arithmetic, algebra, statistics, and more. While it does not have a direct equivalent to ldexp, it offers extensive functionality for various mathematical operations.
big.js is a library for arbitrary-precision decimal arithmetic. It is useful for applications requiring high precision in mathematical calculations. Although it does not specifically provide an ldexp function, it offers precise control over arithmetic operations, which can be useful in similar contexts.
decimal.js is another library for arbitrary-precision decimal arithmetic. It provides a wide range of mathematical functions and operations with high precision. Like big.js, it does not have an ldexp function but offers extensive capabilities for precise arithmetic.
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Multiply a double-precision floating-point number by an integer power of two.
npm install @stdlib/math-base-special-ldexp
var ldexp = require( '@stdlib/math-base-special-ldexp' );
Multiplies a double-precision floating-point number by an integer power of two (i.e., x = frac * 2^exp).
var x = ldexp( 0.5, 3 ); // => 0.5 * 2^3 = 0.5 * 8
// returns 4.0
x = ldexp( 4.0, -2 ); // => 4 * 2^(-2) = 4 * (1/4)
// returns 1.0
If frac equals positive or negative zero, NaN, or positive or negative infinity, the function returns a value equal to frac.
var x = ldexp( 0.0, 20 );
// returns 0.0
x = ldexp( -0.0, 39 );
// returns -0.0
x = ldexp( NaN, -101 );
// returns NaN
x = ldexp( Infinity, 11 );
// returns Infinity
x = ldexp( -Infinity, -118 );
// returns -Infinity
frexp.var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var pow = require( '@stdlib/math-base-special-pow' );
var frexp = require( '@stdlib/math-base-special-frexp' );
var ldexp = require( '@stdlib/math-base-special-ldexp' );
var sign;
var frac;
var exp;
var x;
var f;
var v;
var i;
for ( i = 0; i < 100; i++ ) {
if ( randu() < 0.5 ) {
sign = -1.0;
} else {
sign = 1.0;
}
// Generate a random number:
frac = randu() * 10.0;
exp = round( randu()*616.0 ) - 308;
x = sign * frac * pow( 10.0, exp );
// Break the number into a normalized fraction and an integer power of two:
f = frexp( x );
// Reconstitute the original number:
v = ldexp( f[ 0 ], f[ 1 ] );
console.log( '%d = %d * 2^%d = %d', x, f[ 0 ], f[ 1 ], v );
}
#include "stdlib/math/base/special/ldexp.h"
Multiplies a double-precision floating-point number by an integer power of two (i.e., x = frac * 2^exp).
double x = stdlib_base_ldexp( 0.5, 3 ); // => 0.5 * 2^3 = 0.5 * 8
// returns 4.0
The function accepts the following arguments:
[in] double input value.[in] int32_t integer power of two.double stdlib_base_ldexp( const double frac, const int32_t exp );
#include "stdlib/math/base/special/ldexp.h"
#include "stdlib/math/base/special/frexp.h"
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>
#include <math.h>
static double rand_double() {
int r = rand();
return (double)r / ( (double)RAND_MAX + 1.0 );
}
int main( void ) {
double sign;
double frac;
int32_t exp;
double x;
double v;
int i;
for ( i = 0; i < 100; i++ ) {
if ( rand_double() < 0.5 ) {
sign = -1.0;
} else {
sign = 1.0;
}
// Generate a random number:
frac = rand_double() * 10.0;
exp = (int32_t)( rand_double()*616.0 ) - 308;
x = sign * frac * pow( 10.0, exp );
// Break the number into a normalized fraction and an integer power of two:
stdlib_base_frexp( x, &frac, &exp );
// Reconstitute the original number:
v = stdlib_base_ldexp( frac, exp );
printf( "%e = %lf * 2^%" PRId32 " = %e\n", x, frac, exp, v );
}
}
@stdlib/math-base/special/frexp: split a double-precision floating-point number into a normalized fraction and an integer power of two.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.
See LICENSE.
Copyright © 2016-2023. The Stdlib Authors.
0.1.0 (2023-09-24)
<section class="features">58832ee - update minimum TypeScript version58832ee: update minimum TypeScript version to 4.1
58832ee - feat: update minimum TypeScript version (by Philipp Burckhardt)b734544 - refactor: use strictEqual checks (by Philipp Burckhardt)28e1c84 - docs: resolve C lint errors (by Athan Reines)A total of 2 people contributed to this release. Thank you to the following contributors:
FAQs
Multiply a double-precision floating-point number by an integer power of two.
The npm package @stdlib/math-base-special-ldexp receives a total of 324,444 weekly downloads. As such, @stdlib/math-base-special-ldexp popularity was classified as popular.
We found that @stdlib/math-base-special-ldexp demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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