Integral2 Error message

I am having some difficulty in verifying my answer for an iterated integral. I am looking to solve

>> F = @(x,y) x/y + y/x

F =

  function_handle with value:

    @(x,y)x/y+y/x

>> q = integral2(F,1,2,1,4)

After running it, I have the following error messages:

Error using integral2Calc>integral2t/tensor (line
241)
Integrand output size does not match the input
size.

Error in integral2Calc>integral2t (line 55)
[Qsub,esub] = tensor(thetaL,thetaR,phiB,phiT);

Error in integral2Calc (line 9)
    [q,errbnd] =
    integral2t(fun,xmin,xmax,ymin,ymax,optionstruct);

Error in integral2 (line 106)
    Q =
    integral2Calc(fun,xmin,xmax,yminfun,ymaxfun,opstruct); 
>> 

Is there a way to fix this? I calculated the actual answer to be about 7.27805.

Answer 1

[madhan ravi]

F = @(x,y) x./y + y./x

F = function_handle with value:
    @(x,y)x./y+y./x

q = integral2(F,1,2,1,4)

q = 7.2780

Answer 2

[Saumya Shil]

clear;
close; 
clc;

r=1;
E= @(x) 150*pi*sin(x)/r;
Pds= @(x,y) (E^2)*(r^2)*sin(x)/120*pi;

Wr= integral2(@(x,y)Pds(x,y),0,pi,0,2*pi);
fprintf('\nPower radiated = %fW\n\n',Wr);



I am getting this message.
Error in integral2Calc (line 9)
    [q,errbnd] = integral2t(fun,xmin,xmax,ymin,ymax,optionstruct);

Error in integral2 (line 105)
    Q = integral2Calc(fun,xmin,xmax,yminfun,ymaxfun,opstruct);

Error in untitled (line 9)
Wr= integral2(@(x,y)Pds(x,y),0,pi,0,2*pi);
 

[Steven Lord]

Use element-wise operators in your integrand so your integrand will handle the (usually non-scalar) arrays that integral2 passes into it.

A = [1 2; 3 4]

A = 2×2

1 2 3 4

elementwise = A.^2

elementwise = 2×2

1 4 9 16

array = A^2 % different answer from elementwise

array = 2×2

7 10 15 22

[Walter Roberson]

Pds= @(x,y) (E^2)*(r^2)*sin(x)/120*pi;

likely needs to be

Pds= @(x,y) (E(x).^2) .* (r.^2) .* sin(x) ./120 .* pi;

though I have to wonder if it is intended to be divided by (120*pi) compared to dividing by 120 and multipling the result by pi ?

Answer 3

[Carlos Guerrero García]

syms x y;
int(int(x/y+y/x,1,2),1,4)

ans = 

vpa(ans)

ans = 

7.2780453958794257488809372753109