stdlib-js/math-base-special-rempio2

Compute `x - nπ/2 = r`.

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rempio2

Compute x - nπ/2 = r.

Installation

npm install @stdlib/math-base-special-rempio2

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var rempio2 = require( '@stdlib/math-base-special-rempio2' );

rempio2( x, y )

Computes x - nπ/2 = r.

var y = [ 0.0, 0.0 ];
var n = rempio2( 128.0, y );
// returns 81

var y1 = y[ 0 ];
// returns ~0.765

var y2 = y[ 1 ];
// returns ~3.618e-17

When x is NaN or infinite, the function returns 0 and sets the elements of y to NaN.

var y = [ 0.0, 0.0 ];
var n = rempio2( NaN, y );
// returns 0

var y1 = y[ 0 ];
// returns NaN

var y2 = y[ 1 ];
// returns NaN

y = [ 0.0, 0.0 ];
n = rempio2( Infinity, y );
// returns 0

y1 = y[ 0 ];
// returns NaN

y2 = y[ 1 ];
// returns NaN

Notes

• The function returns n and stores the remainder r as two numbers in y, such that y[0]+y[1] = r.
• For input values larger than 2^20*π/2 in magnitude, the function only returns the last three binary digits of n and not the full result.

Examples

var linspace = require( '@stdlib/array-base-linspace' );
var rempio2 = require( '@stdlib/math-base-special-rempio2' );

var x = linspace( 0.0, 100.0, 100 );
var y = [ 0.0, 0.0 ];
var n;
var i;

for ( i = 0; i < x.length; i++ ) {
    n = rempio2( x[ i ], y );
    console.log( '%d - %dπ/2 = %d + %d', x[ i ], n, y[ 0 ], y[ 1 ] );
}

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C APIs

Usage

#include "stdlib/math/base/special/rempio2.h"

stdlib_base_rempio2( x, &rem1, &rem2 )

Computes x - nπ/2 = r.

#include <stdint.h>

double rem1;
double rem2;

int32_t n = stdlib_base_rempio2( 4.0, &rem1, &rem2 );

The function accepts the following arguments:

• x: [in] double input value.
• rem1: [out] double* destination for first remainder number.
• rem2: [out] double* destination for second remainder number.

int32_t stdlib_base_rempio2( const double x, double *rem1, double *rem2 );

Notes

• The function returns n and stores the remainder r as two numbers in rem1 and rem2, respectively, such that rem1+rem2 = r.

Examples

#include "stdlib/math/base/special/rempio2.h"
#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>

int main( void ) {
    const double x[] = { 0.0, 1.0, 4.0, 128.0 };

    double rem1;
    double rem2;
    int32_t n;
    int i;
    for ( i = 0; i < 4; i++ ) {
        n = stdlib_base_rempio2( x[ i ], &rem1, &rem2 );
        printf( "%lf - %"PRId32"π/2 = %lf + %lf\n", x[ i ], n, rem1, rem2 );
    }
}

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Notice

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.

Community

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Copyright

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