RE: Integration bugs in Mathematica 3.0
- To: mathgroup at smc.vnet.net
- Subject: [mg9341] RE: [mg9213] Integration bugs in Mathematica 3.0
- From: "Richard W. Finley, M. D." <trfin at umsmed.edu>
- Date: Sat, 1 Nov 1997 03:33:27 -0500
- Sender: owner-wri-mathgroup at wolfram.com
Hi Carlos
I use Mathematica 3.01 under Win95. Performing the definite integral
you give as fu, Mathematica gives the answer (after simplifying): BQ
= Sqrt[2](2 + Cos[phiQ]) EllipticK[-2 - 2/(1+Cos[phiQ])]Sqrt[3 +
Sec[phiQ/2]^2]/(5+3 Cos[phiQ])
And BQ/.phiQ->0 gives 3 EllipticK[-3] = 3.23477 which I believe is the
correct answer....??
I don't see the problem. Are you using version 3.00 ? Perhaps this is
something that was fixed in the update?
RF
-----Original Message-----
From: Carlos A. Felippa [SMTP:carlos at mars.Colorado.EDU] To:
mathgroup at smc.vnet.net
Sent: Friday, October 24, 1997 12:00 AM To: mathgroup at smc.vnet.net
Subject: [mg9213] Integration bugs in Mathematica 3.0
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.