# powm1
> Evaluate `bˣ - 1`.
When `b` is close to `1` and/or `x` is small, this implementation is more accurate than naively computing `bˣ` minus `1`.
## Usage
```javascript
var powm1 = require( '@stdlib/math/base/special/powm1' );
```
#### powm1( b, x )
Evaluates `bˣ - 1`.
```javascript
var y = powm1( 2.0, 3.0 );
// returns 7.0
y = powm1( 4.0, 0.5 );
// returns 1.0
y = powm1( 0.0, 100.0 );
// returns -1.0
y = powm1( 100.0, 0.0 );
// returns 0.0
y = powm1( 0.0, 0.0 );
// returns 0.0
y = powm1( 3.141592653589793, 5.0 );
// returns ~305.0197
y = powm1( NaN, 3.0 );
// returns NaN
y = powm1( 5.0, NaN );
// returns NaN
```
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var powm1 = require( '@stdlib/math/base/special/powm1' );
var b;
var x;
var y;
var i;
for ( i = 0; i < 100; i++ ) {
b = round( randu()*10.0 );
x = round( randu()*10.0 ) - 5.0;
y = powm1( b, x );
console.log( '%d^%d - 1 = %d', b, x, y );
}
```
