Expressing the double integral on matlab

Hi everyone,

I' m having a big assignment in matlab

However I don't know how to express double intergral having domain.

For example : Find the surface area of the sphere x^2+y^2+z^2 =9

And my solution is :

z = f(x,y)= square root of 9 - x^2 - y^2

therefore,

f '(x,y)x = -x/squareroot(9-x^2-y^2)

f '(x,y)y = -y/squareroot(9-x^2-y^2)

And we have: (applying the formula of double integral : double integral(squareroot(1+[f '(x,y)x]^2 +[f ' (x,y)y]^2) dA)

S = 2 * double integral(squareroot(1+(-x/squareroot(9-x^2-y^2))^2+(-y/squareroot(9-x^2-y^2))^2) dx dy) (1)

Additionally, x = rcost, y = rsint => D = { 0 <= r <= 3; 0 <= t <= 2pi } (2)

Then replace (2) into (1) and get answer

How can I code double integral with matlab such as example above ??

[madhan ravi]

Did you have a look at https://in.mathworks.com/help/matlab/ref/integral2.html ?

[comment moved to answer]

[Cuong Ho Chi]

Thanks for your support Mr.Madhan

Answer 1

[madhan ravi]

https://in.mathworks.com/matlabcentral/answers/462160-expressing-the-double-integral-on-matlab#comment_705243