tsimplify problem

11212017, 04:10 PM
Post: #1




tsimplify problem
With the beta v2, I tried:
tsimplify(atan(cot(pi*x))) which returned pi*x(1/2)*pi ...which isn't correct to the best of my knowledge (doesn't plot the same). 

11212017, 04:24 PM
Post: #2




RE: tsimplify problem
tsimplify replaces trig expressions with exp and inverse trig with ln then it does simplifications without taking care of complex ln branches, the result is not necessarily valid on the whole complex plane.


11212017, 05:45 PM
(This post was last modified: 11212017 05:46 PM by webmasterpdx.)
Post: #3




RE: tsimplify problem
That doesn't look like what it did here...???
I mean the results are not equivalent to the input function. 

11222017, 10:26 AM
Post: #4




RE: tsimplify problem
Perhaps Parisse should not have said "complex" because (unlike e.g. exp) tan is already periodic on the real line, and so atan has real branches there, separated by multiples of pi.
So the "simplified" answer is correct, up to a multiple pi, which in my opinion is probably as much as you should expect when you are using variable arguments (as opposed to an explicit numerical argument that would allow you to obtain a "principal value"). 

11232017, 03:24 AM
Post: #5




RE: tsimplify problem
True...
Thx 

11232017, 03:30 AM
Post: #6




RE: tsimplify problem
It's actually valid for x in [1,0], and y in [1.5,1.5] approx.
Donald 

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