time-to-botec/js/node_modules/@stdlib/math/base/special/roundn/README.md

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@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.
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# 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 -->