@stdlib/math-base-special-rempio2 NPM

rempio2

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Compute x - nπ/2 = r.

Installation

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

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 ] );
}

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 );
    }
}

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.