20190318 12:47:47 0500  received badge  ● Popular Question (source) 
20180831 12:45:16 0500  commented answer  Sage could be even more clever  How to force the use of 'sympy' backend for simplifying symbolic integrals? Thanks, that was the workaround I was looking for! 
20180816 12:02:38 0500  commented answer  Solved: Why does integrate(psi(y)*f(y),y) return an error but integrate(psi(t,y)*f(t,y),y) works? That's good to know, I'll take it as an exception then  and nothing better to understand the software then a bug being explained! 
20180816 11:56:40 0500  commented answer  Solved: Why does integrate(psi(y)*f(y),y) return an error but integrate(psi(t,y)*f(t,y),y) works? seems to be a whitespace indent Found it! 
20180816 11:54:20 0500  asked a question  Sage could be even more clever  How to force the use of 'sympy' backend for simplifying symbolic integrals? Hi there, I have noticed the following problem: The workaround seems to be using the which always seems to be a good idea as I learned from @Emmanuel Charpentier over here. Now I would like to force the use of TL;DR How can I force sage to pull out these type of exponential constants from the integral with the 
20180816 10:50:40 0500  received badge  ● Good Question (source) 
20180816 10:37:46 0500  commented answer  Solved: Why does integrate(psi(y)*f(y),y) return an error but integrate(psi(t,y)*f(t,y),y) works? Thank you for the quick answer! I struggled to format my post  what are the html tags for the nice verbatim code block? 
20180816 10:25:01 0500  commented answer  Solved: Why does integrate(psi(y)*f(y),y) return an error but integrate(psi(t,y)*f(t,y),y) works? Thank you very much, that is a very thorough answer! Just started playing around with SAGE, didn't expect the underlying cracks to show up that quickly.... Do you think I should file another ticket or can I somehow 'push' yours? 
20180816 10:21:58 0500  received badge  ● Supporter (source) 
20180816 10:21:46 0500  received badge  ● Scholar (source) 
20180813 12:12:26 0500  received badge  ● Nice Question (source) 
20180808 08:33:05 0500  received badge  ● Editor (source) 
20180808 07:43:48 0500  received badge  ● Student (source) 
20180808 07:23:22 0500  asked a question  Solved: Why does integrate(psi(y)*f(y),y) return an error but integrate(psi(t,y)*f(t,y),y) works? Hi there, I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(xy) f(y) {d y} $$ of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:
upon which I get the error message
If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:
there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other builtin functions. TL;DR
Why does Solution
Use sympy backend for symbolic integration as in
