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platform (or version) dependence of int(int()) using syms Mac 10 El Cap R2015b vs. Ubuntu 15.10 R2015a

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Eric Bryant on 9 Mar 2016
Closed: MATLAB Answer Bot on 20 Aug 2021
This code produces a result not containing x1p on Mac 10 El Cap R2015b (a development laptop), where x1p and x2p are just dummy variables of a double definite integral:
e = 0.5; x1 = 0; x2 = 4;
syms x1p x2p
assume(x1p,'real'); assume(x2p,'real');
R = ((x1 - x1p).^2 + (x2 - x2p).^2)^0.5;
int( ...
int( ...
8.0.*((x1 - x1p).^4)./R.^6 - 4.0.*((x1 - x1p).^2)./R.^4 - 1./R.^2, ...
x2p, ...
-e*(1 - x1p^2)^0.5, ...
e*(1 - x1p^2)^0.5 ...
), ...
x1p, ...
-1.0, ...
1.0 ...
)
But, the answer contains x1p for Ubuntu 15.10 R2015a (workhorse desktop). Am I doing something wrong? Or, should I give up because of some issue with R2015a.
I should say that because the integrals are definite, I would normally assume that x1p would be evaluated.
By the way, the results are perfect on the Mac.
Wisdom much appreciated
Walter Roberson on 10 Mar 2016
By the way, the exact solution is
(1/40401 * (23968 * sqrt(67) + 287296)) * arctan(7/(sqrt(67)-2)) + (1/40401 * (23968 * sqrt(67) - 287296)) * arctan(9/(sqrt(67)-2)) + (1/40401 * (23968 * sqrt(67) - 287296)) * arctan(7/(sqrt(67)+2)) + (1/40401 * (23968 * sqrt(67) + 287296)) * arctan(9/(sqrt(67)+2)) - (44/9)*pi
Eric Bryant on 10 Mar 2016
@Walter you're a mench... Maybe I should just be getting the exact solutions on the Mac (?) I have been nervous about this because of the singularity because of 1/R-like terms. (It's actually pretty impressive this works on any platform.)