Fixed the false SYMENGINE_ASSERT.

[wermos]

Fixes #1875.

I removed the unnecessary check for whether the *num == *den in is_canonical. All the existing tests still pass without it.

[isuruf]

I think we should fix #1808 instead of removing this assert.

[wermos]

Hi, thanks for the quick reply. I noticed #1808 after making this PR. You are right, I should probably continue the work on the #1808 branch instead of creating this new one.

However, I have a couple of questions: Why are the checks that is_canonical() performs necessary? What happens if the numerator is equal to the denominator? Also, what exactly does the inverse_tct function do?

[isuruf]

Why are the checks that is_canonical() performs necessary? What happens if the numerator is equal to the denominator?

If numerator == denominator, then it should be pi/2*sign(numerator) and not an ATan instance.