An XCas question....

[parisse]

(10-15-2017 11:11 AM)webmasterpdx Wrote:  Well, what I found nice about wolfram alpha is the fact that I didn't have to create assume() statements beforehand. It did that work for me. In my original post I put a link to an example...it did the integration and said for RE(a)>0. To get it to work on xcas, I had to do an assume(RE(a)>0) first. Often it's hard to know what assumptions to make beforehand....it's often trial and error.

But think how you should do that if there are more than one parameter, you would have to make 4 or 8 ... or 2^n subcases. You can't do that on a CAS in a session or you would experience exponential complexity explosion. Maxima choosed to ask questions to the user (is a positive?), but that does not work if you have a computing kernel disjoint from the interface. Hence you must assume something if you are using parameters. But I disagree that it's a trial and error process, most of the time there are natural assumptions to do on parameters, coming from the model or from an easy mathematical analysis.
Unfortunately more and more people are too lazy to learn the bit of necessary math and prefer to be assisted by tools like wolfram alpha. But at some point they will hit a problem that the tool was not designed to solve, and then they will not be able to solve it because they will not have learned how to do that with simpler problems.