How to solve "A and B must be floating-point scalars"?

Question

Silvio Sapienza 2020-7-1

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评论： Walter Roberson 2020-7-2

Hi! This is my code:

>> syms v w x real
>> j=cos(i*v*x-i*w*sin(x))
 
j =
 
cos(v*x*1i - w*sin(x)*1i)
 
>> J=int(j,0,pi)
 
J =
 
int(cos(v*x*1i - w*sin(x)*1i), x, 0, pi)
 
>> f=w^2*J
 
f =
 
w^2*int(cos(v*x*1i - w*sin(x)*1i), x, 0, pi)
 
>> fh=@f
fh =
  function_handle with value:
    @f
>> F=integral(fh,w,0,inf)
Error using integral (line 85)
A and B must be floating-point scalars.

I do not understand the meaning of the error. Can anyone help me to solve it, please?

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Answer 1

Ameer Hamza 2020-7-2

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https://ww2.mathworks.cn/matlabcentral/answers/558070-how-to-solve-a-and-b-must-be-floating-point-scalars#answer_459793

在 MATLAB Online 中打开

In a symbolic toolbox, you need to use int() instead of integral to find a symbolic integration. Try following code

syms v w x real
j=cos(1i*v*x-1i*w*sin(x));
J=int(j,0,pi);
f=w^2*J;
F=int(f,w,0,inf);

However, the equation is too complex for MATLAB to find a closed-form solution (or such a solution might not exist).

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Walter Roberson 2020-7-2

There is an expression for the inner integral; it can be expressed in terms of the AngerJ https://www.maplesoft.com/support/help/maple/view.aspx?path=AngerJ function, or rather longer hypergeometric or MeijerG forms.

However, I do not find a closed form expression for the overall integral.

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