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# npm

## @stdlib/math-base-special-cfloorn 0.0.5 • Public • Published

# floorn

Round a complex number to the nearest multiple of `10^n` toward negative infinity.

## Installation

`npm install @stdlib/math-base-special-cfloorn`

## Usage

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

#### cfloorn( [out,] re, im, n )

Rounds a `complex` number comprised of a real component `re` and an imaginary component `im` to the nearest multiple of `10^n` toward negative infinity.

```// Round components to 2 decimal places:
var v = cfloorn( -3.141592653589793, 3.141592653589793, -2 );
// returns [ -3.15, 3.14 ]

// If n = 0, `cfloorn` behaves like `cfloor`:
v = cfloorn( -3.141592653589793, 3.141592653589793, 0 );
// returns [ -4.0, 3.0 ]

// Round components to the nearest thousand:
v = cfloorn( -12368.0, 12368.0, 3 );
// returns [ -13000.0, 12000.0 ]

v = cfloorn( NaN, NaN, 0 );
// returns [ NaN, NaN ]```

By default, the function returns real and imaginary components as a two-element `array`. To avoid unnecessary memory allocation, the function supports providing an output (destination) object.

```var Float32Array = require( '@stdlib/array-float32' );

var out = new Float32Array( 2 );

var v = cfloorn( out, -4.2, 5.5, 0 );
// returns <Float32Array>[ -5.0, 5.0 ]

var bool = ( v === out );
// returns true```

## Notes

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

```var x = -0.2 - 0.1;
// returns -0.30000000000000004

// Should round components to 0.3:
var v = cfloorn( x, x, -16 );
// returns [ -0.3000000000000001, -0.3000000000000001 ]```

## Examples

```var Complex128 = require( '@stdlib/complex-float64' );
var randu = require( '@stdlib/random-base-randu' );
var ceil = require( '@stdlib/math-base-special-ceil' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var cfloorn = require( '@stdlib/math-base-special-cfloorn' );

var re;
var im;
var z;
var o;
var w;
var n;
var i;

for ( i = 0; i < 100; i++ ) {
re = ( randu()*100.0 ) - 50.0;
im = ( randu()*100.0 ) - 50.0;
z = new Complex128( re, im );

n = ceil( randu()*5.0 );
o = cfloorn( real(z), imag(z), -n );
w = new Complex128( o[ 0 ], o[ 1 ] );

console.log( 'floorn(%s,%s) = %s', z.toString(), n.toString(), w.toString() );
}```

## 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 ## Keywords

### Install

`npm i @stdlib/math-base-special-cfloorn`

### Repository

github.com/stdlib-js/math-base-special-cfloorn

stdlib.io

8

0.0.5