why is my code not working?

I should make an iterative cylce, yet when trying to run it gives me this error

Array indices must be positive integers or logical values.

for i= linspace(0.0001,0.0009,1000)
     Fm= (0.25).*(((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(i).^-1))))).^-1).*((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(i).^-1)))))).^-1);
     if Fm(i)-Fm(i+1)<= abs(10^-6)
         break
     end
end

Answer 1

[KALYAN ACHARJYA]

i= linspace(0.0001,0.0009,1000)
%.................^ ...........^............

Array indices must be non zero positive integer

like

linspace(1,1,1000)

Aprat from the above issue there is undefined function or variable 'Rey'. Ensure that it is there in your complete code.

[Franco Belletti]

I don't think the problem is the linspace as it gives me the row with values I need Rey is ofcourse defined in my code, but the problem regards the loop, I'd like to know what does the eror mean, again that being

Array indices must be positive integers or logical values. which particulary refers to my If cylce

if Fm(i)-Fm(i+1)<= abs(10^-6)

[KALYAN ACHARJYA]

I have answered based on the error

Array indices must be positive integers or logical values.

With this line space i= linspace(0.0001,0.0009,1000)

if Fm(i)-Fm(i+1)<= abs(10^-6)

This does not work

Say i=0.0001, that is first value

Fm(i)>>Fm(0.0001) does it have any menaing

%...^................^ ...these are called indices of an array, it must be non zero positive interger.

[Franco Belletti]

crystal clear thanks!

[KALYAN ACHARJYA]

Welcome @Franco If your question is answered, you can give credit to the answer by accepting it.

Answer 2

[madhan ravi]

Probably you want (no loops needed):

ii = linspace(0.0001,0.0009,1000);
Fm = (0.25).*(((log((2.7*10^-5)+...
    (2.51.*((Rey.*sqrt(ii).^-1))))).^-1).*((log((2.7*10^-5)...
    +(2.51.*((Rey.*sqrt(ii).^-1)))))).^-1);
First_encounter = find(abs(Fm(1:end-1)...
    -Fm(2:end))<= 1e-6,1,'first')