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4 years ago | asked a question | Assume expression to be noninteger Hello! How to assume expression to be an integer? I try to do some symbolic integration while Sage asks to provide additional info about expression. MWE: gives:
How to assume that
Thanks! |
7 years ago | commented answer | Substitution of subexpression Interesting and confusing.. Why do I have to include w in subexpression? |
7 years ago | asked a question | Substitution of subexpression Hi! My task is to derive some expression and then find subexpressions in it and substitute. In details I need to find derivative of psi and then substitute expressions back. The way I found this derivative looks ugly but I suppose it's easier to do substitution in such form of expression. −2(wxcos(tw)+wysin(tw))(παcos(πy2a)sin(2πx2a)a2+2πβcos(2πy2a)sin(πx2a)a2)+ +2(wycos(tw)−wxsin(tw))(πβcos(πx2a)sin(2πy2a)a2+2παcos(2πx2a)sin(πy2a)a2) Then I need to substitute xcos(wt) + ysin(wt) to x2 and ycos(wt) - xsin(wt) to y2 for further integration over x2 and y2. Unfortunately, I didn't understand how to do this except that I need to use wild cards. So $0(xcos(tw)+ysin(tw))+$1(ycos(tw)−xsin(tw)) which is looks pretty the same but somehow don't match: gives None. Could someone explain what is going on or maybe I should use something else? |