croundn

Round each component of a double-precision complex floating-point number to the nearest multiple of 10^n.

Usage

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

croundn( z, n )

Rounds each component of a double-precision complex floating-point number to the nearest multiple of 10^n.

var Complex128 = require( '@stdlib/complex/float64/ctor' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );

var v = croundn( new Complex128( -3.141592653589793, 3.141592653589793 ), -2 );
// returns <Complex128>

var re = real( v );
// returns -3.14

var im = imag( v );
// returns 3.14

v = croundn( new Complex128( -3.141592653589793, 3.141592653589793 ), 0 );
// returns <Complex128>

re = real( v );
// returns -3.0

im = imag( v );
// returns 3.0

v = croundn( new Complex128( -12368.0, 12368.0 ), 3 );
// returns <Complex128>

re = real( v );
// returns -12000.0

im = imag( v );
// returns 12000.0

v = croundn( new Complex128( NaN, NaN ), 3 );
// returns <Complex128>

re = real( v );
// returns NaN

im = imag( v );
// returns NaN

Notes

When operating on floating-point numbers in bases other than 2, rounding to specified digits can be inexact. For example,

var Complex128 = require( '@stdlib/complex/float64/ctor' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );

var x = 0.2 + 0.1;
// returns 0.30000000000000004

// Should round components to 0.3:
var v = croundn( new Complex128( x, x ), -16 );
// returns <Complex128>

var re = real( v );
// returns 0.3000000000000001

var im = imag( v );
// returns 0.3000000000000001

Examples

var uniform = require( '@stdlib/random/base/uniform' ).factory;
var Complex128 = require( '@stdlib/complex/float64/ctor' );
var floor = require( '@stdlib/math/base/special/floor' );
var croundn = require( '@stdlib/math/base/special/croundn' );

var rand1 = uniform( -5.0, 0.0 );
var rand2 = uniform( -50.0, 50.0 );

var z;
var i;
var n;
for ( i = 0; i < 100; i++ ) {
    z = new Complex128( rand2(), rand2() );
    n = floor( rand1() );
    console.log( 'croundn(%s, %s) = %s', z, n, croundn( z, n ) );
}

C APIs

Usage

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

stdlib_base_croundn( z, n )

Rounds each component of a double-precision complex floating-point number to the nearest multiple of 10^n.

#include "stdlib/complex/float64/ctor.h"
#include "stdlib/complex/float64/real.h"
#include "stdlib/complex/float64/imag.h"

stdlib_complex128_t z = stdlib_complex128( -3.141592653589793, 3.141592653589793 );

stdlib_complex128_t out = stdlib_base_croundn( z );

double re = stdlib_complex128_real( out );
// returns -3.14

double im = stdlib_complex128_imag( out );
// returns 3.14

The function accepts the following arguments:

z: [in] stdlib_complex128_t input value.
n: [in] int32_t integer power of 10.

stdlib_complex128_t stdlib_base_croundn( const stdlib_complex128_t z, const int32_t n );

Examples

#include "stdlib/math/base/special/croundn.h"
#include "stdlib/complex/float64/ctor.h"
#include "stdlib/complex/float64/reim.h"
#include <stdio.h>

int main( void ) {
    const stdlib_complex128_t x[] = {
        stdlib_complex128( 3.14, 1.5 ),
        stdlib_complex128( -3.14, -1.5 ),
        stdlib_complex128( 0.0, 0.0 ),
        stdlib_complex128( 0.0/0.0, 0.0/0.0 )
    };

    stdlib_complex128_t v;
    stdlib_complex128_t y;
    double re1;
    double im1;
    double re2;
    double im2;
    int i;
    for ( i = 0; i < 4; i++ ) {
        v = x[ i ];
        y = stdlib_base_croundn( v, -2 );
        stdlib_complex128_reim( v, &re1, &im1 );
        stdlib_complex128_reim( y, &re2, &im2 );
        printf( "croundn(%lf + %lfi) = %lf + %lfi\n", re1, im1, re2, im2 );
    }
}