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Noncentral chi-square inverse cumulative distribution function


X = ncx2inv(P,V,DELTA)


X = ncx2inv(P,V,DELTA) returns the inverse of the noncentral chi-square cdf using the corresponding degrees of freedom in V and positive noncentrality parameters in DELTA, at the corresponding probabilities in P. P, V, and DELTA can be vectors, matrices, or multidimensional arrays that all have the same size, which is also the size of X. A scalar input for P, V, or DELTA is expanded to a constant array with the same dimensions as the other inputs.


ncx2inv([0.01 0.05 0.1],4,2)
ans =
  0.4858  1.1498  1.7066


ncx2inv uses Newton's method to converge to the solution.


[1] Evans, M., N. Hastings, and B. Peacock. Statistical Distributions. 2nd ed., Hoboken, NJ: John Wiley & Sons, Inc., 1993, pp. 50–52.

[2] Johnson, N., and S. Kotz. Distributions in Statistics: Continuous Univariate Distributions-2. Hoboken, NJ: John Wiley & Sons, Inc., 1970, pp. 130–148.

Version History

Introduced before R2006a