stdlib-js
<summary>
About stdlib...
</summary>
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roundn
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
Round a double-precision floating-point number to the nearest multiple of 10^n.
bash
npm install @stdlib/math-base-special-roundn
javascript
var roundn = require( '@stdlib/math-base-special-roundn' );
#### roundn( x, n )
Rounds a double-precision floating-point number to the nearest multiple of 10^n.
javascript
// Round a value to 2 decimal places:
var v = roundn( 3.141592653589793, -2 );
// returns 3.14
// If n = 0, `roundn` behaves like `round`:
v = roundn( 3.141592653589793, 0 );
// returns 3.0
// Round a value to the nearest thousand:
v = roundn( 12368.0, 3 );
// returns 12000.0
2, rounding to specified digits can be inexact. For example,
javascript
var x = 0.2 + 0.1;
// returns 0.30000000000000004
// Should round to 0.3...
var v = roundn( x, -16 );
// returns 0.3000000000000001
javascript
var randu = require( '@stdlib/random-base-randu' );
var roundn = require( '@stdlib/math-base-special-roundn' );
var x;
var n;
var v;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*100.0) - 50.0;
n = roundn( randu()*5.0, 0 );
v = roundn( x, -n );
console.log( 'x: %d. Number of decimals: %d. Rounded: %d.', x, n, v );
}
c
#include "stdlib/math/base/special/roundn.h"
#### stdlib_base_roundn( x, n )
Rounds a double-precision floating-point number to the nearest multiple of 10^n.
c
double y = stdlib_base_roundn( 3.14, -2 );
// returns 3.14
The function accepts the following arguments:
- x: [in] double input value.
- n: [in] int32_t integer power of 10.
c
double stdlib_base_roundn( const double x, const int32_t n );
c
#include "stdlib/math/base/special/roundn.h"
#include <stdio.h>
int main( void ) {
const double x[] = { 3.14, -3.14, 0.0, 0.0/0.0 };
double y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_roundn( x[ i ], -2 );
printf( "roundn(%lf) = %lf\n", x[ i ], y );
}
}
@stdlib/math-base/special/ceiln][@stdlib/math/base/special/ceiln]: round a numeric value to the nearest multiple of 10^n toward positive infinity.
- [@stdlib/math-base/special/floorn][@stdlib/math/base/special/floorn]: round a double-precision floating-point number to the nearest multiple of 10^n toward negative infinity.
- [@stdlib/math-base/special/round][@stdlib/math/base/special/round]: round a numeric value to the nearest integer.
- [@stdlib/math-base/special/roundb][@stdlib/math/base/special/roundb]: round a numeric value to the nearest multiple of b^n on a linear scale.
