??? Error: Unexpected MATLAB operator.

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XIONG Qingxiang
XIONG Qingxiang 2019-7-10
评论： XIONG Qingxiang 2019-7-10
Hello everyone,
I'm cofused by this problem for several days. here is the error message:
??? Error: Unexpected MATLAB operator.
Error in ==> sym.eval at 15
s = evalin('caller',vectorize(map2mat(char(x))));
Error in ==> test_nmt_m2 at 80
J1 = eval(feval(symengine,'numeric::int',f4,'r=lower3..upper3')) + ...
Here is the code which producing the error:
J1 = eval(feval(symengine,'numeric::int',f4,'r=lower3..upper3')) + ...
eval(feval(symengine,'numeric::int',f2,'r=lower1..upper1')) + ...
eval(feval(symengine,'numeric::int',f3,'r=lower5..upper5')) + ...
eval(feval(symengine,'numeric::int',f4,'r=lower2..upper2'));
Thanks in advance if anybody can solve this problem.

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采纳的回答

Walter Roberson
Walter Roberson 2019-7-10
Never eval() a symbolic expression. The language they use is not MATLAB and is not mupad.
I suspect that numeric integration is failing for you, returning back an unevaluated numeric::int form.
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Walter Roberson
Walter Roberson 2019-7-10
vpaintegral()
However any numeric integral can fail as the code can detect no convergence to within available numeric accuracy. Numeric integration across a singularity is not any more possible than theoretical integration across the singularity.
XIONG Qingxiang
XIONG Qingxiang 2019-7-10
Thank you very much!
That's exactly the answer what I am looking for. For the case of non-monotonic, it can work for one time, when it comes to loop, for example, two or three times, it fails. So in the case of non-monotonic, what else method should I use for integration when it's divergence?

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