Implementing while loop in Heun's Method

For dh/dt=-k√H where k is = 0.06

how can I implement while loop (while H>0) in Heun's method to find the time taken for the tank to drain ?. given the initial value of H is 4

Thanks for the help in advance

Answer 1

[Alan Stevens]

Here's a rough and ready way (I'll leave you to implement Heun's method):

f = @(H) -0.06*sqrt(H);
H = 4;
t = 0;
dt = 0.1;  % choose your own value
while H>0
      t = t+dt;
      % Use Heun's method to get H at t+dt      
end
disp(t) % time to drain

Note that, because of the square root, the last step is likely to result in a complex value for the final value of H.