## a bug in interim.tsd.in()? [Two-Stage / GS Designs]

Dear Ben,

Thank you for explanations!
As I mentioned above, I was not aware that Maurer method is not just another set of alphas. After reading the manuscript I understood the concept.
I tried to simulate some data to show the approach of safety net with inverse normal vs fixed (Helmut is right, it is very popular in Russia last days as my colleagues said; of course the Sponsors are using Potvin C )

But my loop was interrupted:
interim.tsd.in(GMR1=0.89, CV1=0.2575165, n1=38) Error in tval[, 1] : incorrect number of dimensions In addition: Warning messages: 1: In qnorm(p2) : NaNs produced 2: In min(df) : no non-missing arguments to min; returning Inf

What is going on here?
I thought the problem with GMR1<0.9, tried to add some condition to omit the replicates with GMR1<0.9, but even that case got the same error for some replicates.

Kind regards,
Mittyri