# boxcox1pinv
> Compute the inverse of a one-parameter [Box-Cox transformation][box-cox-transformation] for `1+x`.
To compute the inverse of a one-parameter [Box-Cox transformation][box-cox-transformation], one finds the `x` such that
## Usage
```javascript
var boxcox1pinv = require( '@stdlib/math/base/special/boxcox1pinv' );
```
#### boxcox1pinv( y, lambda )
Computes the inverse of a one-parameter [Box-Cox transformation][box-cox-transformation] for `1+x`.
```javascript
var v = boxcox1pinv( 1.0, 2.5 );
// returns ~0.6505
v = boxcox1pinv( 4.0, 2.5 );
// returns ~1.6095
v = boxcox1pinv( 10.0, 2.5 );
// returns ~2.6812
v = boxcox1pinv( 2.0, 0.0 );
// returns ~6.3891
v = boxcox1pinv( -1.0, 2.5 );
// returns NaN
v = boxcox1pinv( 0.0, -1.0 );
// returns 0.0
v = boxcox1pinv( 1.0, NaN );
// returns NaN
v = boxcox1pinv( NaN, 3.1 );
// returns NaN
```
## Examples
```javascript
var incrspace = require( '@stdlib/array/incrspace' );
var boxcox1pinv = require( '@stdlib/math/base/special/boxcox1pinv' );
var y = incrspace( -1.0, 10.0, 1.0 );
var l = incrspace( -0.5, 5.0, 0.5 );
var b;
var i;
var j;
for ( i = 0; i < y.length; i++ ) {
for ( j = 0; j < l.length; j++ ) {
b = boxcox1pinv( y[ i ], l[ j ] );
console.log( 'boxcox1pinv(%d, %d) = %d', y[ i ], l[ j ], b );
}
}
```
## References
- Box, G. E. P., and D. R. Cox. 1964. "An Analysis of Transformations." _Journal of the Royal Statistical Society. Series B (Methodological)_ 26 (2). \[Royal Statistical Society, Wiley]: 211–52. .
[box-cox-transformation]: https://en.wikipedia.org/wiki/Power_transform#Box-Cox_transformation
