# evaluate the double integration

3 views (last 30 days)
john on 20 Sep 2022
Commented: john on 20 Sep 2022
May I know I would like to evaluate the double integral of the function and why this error happens and how do I perform the integration?  Abolfazl Chaman Motlagh on 20 Sep 2022
You got 2 things wrong (i think) . the error you currently get is for second one. but you will get the error for first one eventually.
first, upper limit of integral shouldn't be function of variable a. because in that case the result of integral would be function of a.
and the other problem is in integral2 function the integration over y (second argument) is first integration so you should change the orders.
syms r theta;
a = 1; %%%%%%%%%%%%%%%%%%%%%%%%
theta_u = -(pi/2);
theta_v = pi/2;
r_u = 0;
r_v = @(theta) (a*cos(theta));
y = @(theta,r) (4 * r.^2 .* cos(theta));
integral2(y,theta_u,theta_v,r_u,r_v)
ans = 1.5708
john on 20 Sep 2022
thanks! you solved the problem

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