differential equations without ode solvers

hello, I am trying to simulate running two differential equaitons at the same time but there is an error that index exceeds array bounds:

The code am using is given in the following:

dt=0.5;

t=0:dt:10;

h1=zeros(size(t));

h1(1)=0;

h2=zeros(size(t));

h2(1)=0;

for i=1:21

if h1(i) < 1

h1= 0.5-0.065*sqrt(h1(i));

h2= 0.065*sqrt(h1(i)) - 0.1*sqrt(h2(i));

h1(i+1)= h1(i)+dt*h1;

h2(i+1)=h2(i)+dt*h2;

else h1(i)=1;

end

Answer 1

[Alex Mcaulley]

I think you are overwriting h1 and h2 variables in:

h1= 0.5-0.065*sqrt(h1(i));
h2= 0.065*sqrt(h1(i)) - 0.1*sqrt(h2(i));

After those lines h1 and h2 are scalars. Probably you need to put:

h1(i)= 0.5-0.065*sqrt(h1(i));
h2(i)= 0.065*sqrt(h1(i)) - 0.1*sqrt(h2(i));

[Taleb Bou Hamdan]

Thank you. I have the names of the functions from h1 h2 to f1 and f2 and this solved the problem