??? Error: Unexpected MATLAB operator.

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.

Answer 1

[Walter Roberson]

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.

[XIONG Qingxiang]

Thank you so much.

BUT how to modify this integration?

Besides it works well when the integrand is monotonic. I mean sometimes it works, but sometimes the error occurs.

[Walter Roberson]

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]

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?