Need to solve an singlevariable integral of functions of two variables, and get answers as functions

Question

Ori Iger 2020-5-5

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评论： Matt J 2020-5-6

Hello and thanks

I've done this before, but now am getting an error like

Error using integralCalc/finalInputChecks (line 522)
Input function must return 'double' or 'single' values. Found 'sym'.
Error in integralCalc/iterateScalarValued (line 315)
                finalInputChecks(x,fx);
Error in integralCalc/vadapt (line 132)
            [q,errbnd] = iterateScalarValued(u,tinterval,pathlen);
Error in integralCalc (line 103)
        [q,errbnd] = vadapt(@minusInfToInfInvTransform,interval);

when doing

Sol_Mex_P_22 = @(J) abs(integral(@(t) K_mex_p(t).*CC22(t,J),-Inf,Inf));

what is wrong??

thanks!

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Answer 1

Matt J 2020-5-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/523193-need-to-solve-an-singlevariable-integral-of-functions-of-two-variables-and-get-answers-as-functions#answer_430579

在 MATLAB Online 中打开

This function

@(t) K_mex_p(t).*CC22(t,J)

needs to return a numeric value for every given t. It is returning a symbolic value, however.

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Ori Iger 2020-5-6

Thanks! I understood that, but how can I solve the integral solely depending on t (from -info to inf so no t remains), and get the answer only as function of J?

I actually did this already, with this same integral function, and it worked great actually. Maybe the J dependence of CC22 is too complicated this time? Uri

Matt J 2020-5-6

No, the failure here is because CC22 is a symbolic expression or a symbolic value for J was given as input. All variables participating in this computation must be non-symbolic. If you need to do symbolic integration, then you would use int,

https://www.mathworks.com/help/symbolic/int.html

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