why is my code not working?

I'd like to get the index (i) for wich the condition I set in the foor loop appears on the results

Fm0= linspace(0.01,0.02,100);
 %ciclo iterativo

for i=1:100
    for Fm= (0.25).*(((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm0).^-1))))).^-1).*((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm0).^-1)))))).^-1)
        if Fm(i)-Fm0<=10^-6
            break
        end
    end
end

Answer 1

[Walter Roberson]

Fm0 = linspace(0.01,0.02,100);
Fm= (0.25).*(((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm0).^-1))))).^-1).*((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm0).^-1)))))).^-1)
i = find( Fm-Fm0 <= 10^-6, 1);

You will find that the answer is 1 -- Fm0(1) > Fm(1) so the subtraction is negative and so satisfies the condition.

You might perhaps have been thinking,

i = find( abs(Fm-Fm0) <= 10^-6, 1);

but you will find that this is empty.

[Franco Belletti]

thanks!

[Walter Roberson]

If you are looking for the value of Fm such that

Fm = (0.25).*(((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm).^-1))))).^-1).*((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm).^-1)))))).^-1)

then the value turns out to be complex, at least for positive Rey (I did not experiment with negative Rey.)