From: SourceForge.net <no...@so...> - 2011-12-04 19:59:50
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Bugs item #3397562, was opened at 2011-08-24 10:31 Message generated for change (Comment added) made by dgildea You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3397562&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: https://www.google.com/accounts () Assigned to: Nobody/Anonymous (nobody) Summary: sin(x^2)/(x^2) improper integral incorrect? Initial Comment: (%i1) integrate(sin(x^2)/(x^2),x,1,inf); defint: integral is divergent. This used to just return the integral as a nounform. Numerical approximation says it's about 0.2862504407259549. Thanks! ---------------------------------------------------------------------- >Comment By: Dan Gildea (dgildea) Date: 2011-12-04 11:59 Message: Seems to be caused by the following problem with limit: (%i2) limit( gamma_incomplete(-1/2, -%i*x^2), x, inf); (%o2) gamma_incomplete(-1/2,infinity) ---------------------------------------------------------------------- Comment By: https://www.google.com/accounts () Date: 2011-12-02 07:56 Message: According to Laurent Fousse, it was caused by commit 59775311e53ef8a8fb5a3ad067a6c1cc153075d2 (see http://trac.sagemath.org/sage_trac/ticket/11737) ---------------------------------------------------------------------- Comment By: https://www.google.com/accounts () Date: 2011-12-02 07:45 Message: I was using 5.25.0. And (%i3) quad_qagi(sin(x^2)/(x^2),x,1,inf); ***MESSAGE FROM ROUTINE DQAGI IN LIBRARY SLATEC. ***INFORMATIVE MESSAGE, PROG CONTINUES, TRACEBACK REQUESTED * ABNORMAL RETURN * ERROR NUMBER = 1 * ***END OF MESSAGE (%o3) [.2852680980196833, .007186678748743569, 5985, 1] And Wolfram Alpha gives, for input integrate(sin(x^2)/x^2,x,1,inf) sqrt(pi/2) (1-2 C(sqrt(2/pi)))+sin(1)~~0.285737 where C is a Fresnel integral. ---------------------------------------------------------------------- Comment By: Raymond Toy (rtoy) Date: 2011-08-24 10:59 Message: What version are you using? The current version returns -%i*gamma_incomplete(-1,2*%i)/2+%i*gamma_incomplete(-1,-2*%i)/2+1/2 This is approximately .6734567682657728. quad_qagi also says the integral is approximately 0.67335. Marking this as pending/worksforme ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3397562&group_id=4933 |