student_t_cdf returning 0.0 when should be returning actual value #3234

Hi, it appears student_t_cdf() returns 0.0 in cases where it shouldn't.
I have attached session output showing mismatched values - p-values using student_t_cdf() against R's t.test. Most match almost exactly but where they do not, student_t_cdf() appears to return exactly 0.0 rather than a computed value.

I have attached session output and a self-contained example (just source this into R). I hope it's not a coding mistake on my part, don't think so.

thanks
Fraser

output.txt

issue_git_R.txt