HOME and CAS unexpected behavior

10212022, 08:35 PM
Post: #1




HOME and CAS unexpected behavior
Hi all,
One of my students mentioned to me that he was getting zero when calculating the result of a finite integral in HOME. I already had the solutionI calculated using a table of integrals so I could easily evaluate it in both HOME and CAS, and, lo and behold, I get 0.000E0 in HOME, 7.1054E15 in CAS. The expression to evaluate is EXP(2r/a) * (2r^2/a^2  2r/a  1) + 1 with r=0.877E15 and a =5.290E11 Any idea where is this behavior coming from?[/code] 

10222022, 06:04 PM
(This post was last modified: 10222022 06:12 PM by rawi.)
Post: #2




RE: HOME and CAS unexpected behavior
What are the lower and upper limit of the integral? And what is the variable to integrate?


10222022, 07:13 PM
Post: #3




RE: HOME and CAS unexpected behavior
(10212022 08:35 PM)mmadurga Wrote: I already had the solutionI calculated using a table of integrals so I could easily evaluate it in both HOME and CAS, and, lo and behold, I get 0.000E0 in HOME, 7.1054E15 in CAS. Since you use table of integrals, I assumed it has nothing to do with integration routine. It may be due to massive cancellations, for F(hi)  F(lo) HOME has 12 decimals precisions, but CAS has more (535 = 48bits, or about 14+ decimals) 

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