Timeout issue using Int PRT

[mrseanman]

Using the Int PRT test, there is a timeout issue when trying to detect incorrect answers for quite simple expressions. It has something to do with large-ish exponents within trig functions.

Here are some examples where this timeout occurs

• correct_ans: sin(x^12/%pi) + C, submitted_ans: 3*sin(x^12/%pi) + C
• correct_ans: cos(x^12/%pi) + C, submitted_ans: 3*cos(x^12/%pi) + C

And some where the timeout does not occur (wrong answer correctly detected).

• correct_ans: sin(x^12) + C, submitted_ans: 3*sin(x^12) + C
• correct_ans: cos(x^12) + C, submitted_ans: 3*cos(x^12) + C
• correct_ans: sin(x^11/%pi) + C, submitted_ans: 3*sin(x^11/%pi) + C

Lower (than 11) values of exponents are also well behaved. For all of the above the test option is set to x.

Correct answers are detected OK, answers without a constant are detected OK. Only these incorrect answers with a constant cause this issue.

[sangwinc]

Interesting edge case! This is caused because, internally, the system was calling trigexpand of sin(2^12/%pi). This obviously causes a timeout! For a non-timeout example, try trigexpand(sin(2^3/%pi)); in Maxima to see why this leads to expression explosion. Thanks for reporting it.