Distribution function of the non central F-distribution
doublyF_opt(x, df1, df2, lambda1, lambda2, acc = 100, ex = 5)
quantile, a single numeric value
first degree of freedom, a single integer value
second degree of freedom, a single integer value
first non centrality parameter, a single numeric value
second non centrality parameter, a single numeric value
accuracy; last index of the approximation of the infinite sum
exactness; break early, if the summands are smaller than 10^(-ex)
Probability of observing a value larger than x