How to replace variables ?

This is my script

   syms x y z dS
  z = sqrt(100 - x.^2 - y.^2)
  zx = diff(z,x)
  zy = diff(z,y)
  dS=sqrt(1+zx.^2+zy.^2)
  fun = @(x,y)(x+y+sqrt(100-x.^2-y.^2).*dS)

And this appear when i run it .....

          >> Untitled3

    z =

    (- x^2 - y^2 + 100)^(1/2)

    zx =

    -x/(- x^2 - y^2 + 100)^(1/2)

    zy =

    -y/(- x^2 - y^2 + 100)^(1/2)

    dS =

    (1 - y^2/(x^2 + y^2 - 100) - x^2/(x^2 + y^2 - 100))^(1/2)

    fun = 

        @(x,y)(x+y+sqrt(100-x.^2-y.^2).*dS)

So here's my problem , i have aldready set dS = sqrt(...) but Matlab doesn't replace dS in my fun function . How do I solve this ? Thank you

[KSSV]

Please attach your code.....either copy paste or attach it as a file....image snippet doesn't help us to help you.

[John Armitage]

okay , i edited it , thanks

Answer 1

[Andrei Bobrov]

syms x y
z = sqrt(100 - x.^2 - y.^2);
zx = diff(z,x);
zy = diff(z,y);
dS=sqrt(1+zx.^2+zy.^2);

fun = subs(x+y+sqrt(100-x.^2-y.^2).*dS);
f = matlabFunction(fun);
M = integral2(f,0,10,0,@(x)sqrt(100-x.^2));

[John Armitage]

thank you very much ! :D