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 ??
Best Answer