# ceilb
> Round a numeric value to the nearest multiple of b^n toward positive infinity.
## Usage
```javascript
var ceilb = require( '@stdlib/math/base/special/ceilb' );
```
#### ceilb( x, n, b )
Rounds a `numeric` value to the nearest multiple of `b^n` toward positive infinity.
```javascript
// Round a value to 4 decimal places:
var v = ceilb( 3.141592653589793, -4, 10 );
// returns 3.1416
// If n = 0 or b = 1, `ceilb` behaves like `ceil`:
v = ceilb( 3.141592653589793, 0, 2 );
// returns 4.0
// Round a value to the nearest multiple of two toward positive infinity:
v = ceilb( 5.0, 1, 2 );
// returns 6.0
```
## Notes
- Due to rounding error in [floating-point numbers][ieee754], rounding may **not** be exact. For example,
```javascript
var x = 0.2 + 0.1;
// returns 0.30000000000000004
// Should round to 0.3...
var v = ceilb( x, -16, 10 );
// returns 0.3000000000000001
```
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var pow = require( '@stdlib/math/base/special/pow' );
var ceilb = require( '@stdlib/math/base/special/ceilb' );
var x;
var n;
var b;
var v;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*100.0) - 50.0;
n = round( (randu()*10.0) - 5.0 );
b = round( randu()*10.0 );
v = ceilb( x, n, b );
console.log( 'x: %d. %d^%d: %d. Rounded: %d.', x, b, n, pow( b, n ), v );
}
```
[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985