Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Problem with Symbolic Math Date: Sat, 23 May 2009 22:26:01 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 22 Message-ID: <gv9t5p$qk1$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-02-blr.mathworks.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1243117561 27265 172.30.248.37 (23 May 2009 22:26:01 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Sat, 23 May 2009 22:26:01 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1852458 Xref: news.mathworks.com comp.soft-sys.matlab:542084 Hi Friends, This problem is to be solved by symbolic math but the solution it gives me does not tally with what the actual solution should be: The problem is to integrate a symbolic function of x, y, w and t with respect to x and evaluate the integrand from -pi/2 to pi/2. So the code below was written: syms N x y w t real A = N*cos(x-y)*cos(w*t-y); B = int(A, x, -pi/2, pi/2); The expected solution is: B should equal N*sin(x-y)*cos(w*t-y) evaluated at (x=pi/2) minus same expression evaluated at (x=-pi/2). Naturally, the final solution should be: B = N*(sin(pi/2-y) - sin(-pi/2-y))*cos(w*t-y) = 2*N*cos(y)*cos(w*t-y). Symbolic toolbox gives me: B = N*cos(-w*t+2*y)+N*cos(w*t) I cannot see how this solution is correct. Please I need this clarified so as to continue using this wonderful tool.