The CHIINV function returns the inverse of the one-tailed probability of the chi-squared distribution. CHIINV uses an iterative algorithm for calculating the result. If CHIINV does not converge (accuracy within +/- 3x10^7) after 100 iterations, the function returns #N/A! error.
If @p < 0 or @p > 1 or @dof < 1 CHIINV returns #NUM! error.