Using convergence for a fixed root iteration

I am trying to write a code that following this procedure:

1. Guess theta = 0
2. Find Cl from L = W*cos(theta) so L = W
3. Find Cd (where Cd is dependent on Cl)
4. Find D from Cd
5. Find theta as theta = asin(T-D/W)
6. Use this new guess for theta and interate from step 2 until convergence of theta.

T (thrust) ias found by calling a function, W = 35000.

How would I write a code to find theta to plug it back in for Cl?