<!-- @license Apache-2.0 Copyright (c) 2018 The Stdlib Authors. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> # roundn > Round a numeric value to the nearest multiple of 10^n. <section class="usage"> ## Usage ```javascript var roundn = require( '@stdlib/math/base/special/roundn' ); ``` #### roundn( x, n ) Rounds a `numeric` value 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 ``` </section> <!-- /.usage --> <section class="notes"> ## Notes - When operating on [floating-point numbers][ieee754] in bases other than `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 ``` </section> <!-- /.notes --> <section class="examples"> ## Examples <!-- eslint no-undef: "error" --> ```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 ); } ``` </section> <!-- /.examples --> <section class="links"> [ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985 </section> <!-- /.links -->