Integration bugs in Mathematica 3.0
- To: mathgroup at smc.vnet.net
- Subject: [mg9213] Integration bugs in Mathematica 3.0
- From: carlos at mars.Colorado.EDU (Carlos A. Felippa)
- Date: Fri, 24 Oct 1997 01:00:28 -0400
- Organization: University of Colorado, Boulder
- Sender: owner-wri-mathgroup at wolfram.com
In a recent FEM project assigned as HW, about one third of the Integrate
results (216 out of roughly 600) were wrong. Extracted sample:
fu=(2+Cos[phiQ])/Sqrt[6-2*Cos[phiQ]*(-2+Cos[theta])-4*Cos[theta]];
BQ=Integrate[fu,{theta,0,Pi}];
Print["BQ=",BQ//InputForm];
fu=fu/.{phiQ->0};
BQ=Integrate[fu,{theta,0,Pi}];
Print["BQ=",BQ//InputForm];
Results:
BQ=0 (* wrong *)
BQ=3*EllipticK[-3] (* demonstrates bug *)
The students were not amused. 2.2 does it right, but most of them did
not have access to it on campus machines.
Further, Integrate takes 2-5 times longer than in 2.2.