BoxCoxInv transformation function
BOXCOXINV(x,lambda,shift) calculates the inverse of the Box-Cox transformation of x with parameters lambda and shift.
The argument x can be a single number or a matrix. When it is a matrix, the function returns a matrix with the same dimensions and with the BOXCOXINV back-transformation applied to all elements.
The shift parameter should not be 0 when x is larger than 0.
The Box-Cox transformation is defined as follows:
The back-transformation, or inverse, is defined as follows: