??? Subscript indices must either be real positive integers or logicals.

hi, i'm using m file in cell mode to solve f(x)=sin (x), where x = 0.8 and i'm getting "??? Subscript indices must either be real positive integers or logicals. " error how it can be solved

[Gijs van Oort]

Please tell us the exact code you're using. Is it actually Matlab code? The code you're giving ('solve f(x)=sin(x)' ) is not Matlab compatible.

Answer 1

[John Doe]

Is this what you're trying to do?

%%Don't run this part
A = magic(4);

%%Run this part by itself
x = 0.8;
f = sin(x)

%%Not this part
A = rand(4);

What you do is: Place your cursor in the middle section. Then press Ctrl + Enter.

Please watch this video:

http://blogs.mathworks.com/videos/2011/07/26/starting-in-matlab-cell-mode-scripts/

[ghassan]

yes but in an " m file "

[John Doe]

There is no difference. Write the two lines in an M-file, save it and run it (either press F5, or write the name of the file in the command window in matlab). If you for some reason want a function (which doesn't make much sense, since it is built-in):

function f = calculate_sin(x)
f = sin(x);
end

Then run the function from Matlab:

f = calculate_sin(0.8);

[ghassan]

ok, so what is the solution using the cell mode in the m file for this problem ???!

[John Doe]

Check my updated answer: I assume you have a script that does more than one thing.

What you do is: Insert %% above the part of the code you want to run, and below it.

Press Ctrl + Enter, when your cursor is in your desired section. And that's that.

Please watch this video:

http://blogs.mathworks.com/videos/2011/07/26/starting-in-matlab-cell-mode-scripts/

[ghassan]

thanks alot :-)

[ghassan]

%% x= 0.8; f = x^2 ; exact = 2*x; for k=1:10; h(k)=10^-k; end for k=1:10; fapp(x)=((x+h(k)^2)-x^2)/h(k); end fapp error = abs (exact-fapp)

im trying to use this code in cell mode and the following error appears

??? Subscript indices must either be real positive integers or logicals.

[Jan]

Please, ghassan, format your code properly. Follow the "? Help" link to learn how to use the forum's interface. Thanks.

It would be helpful, if you post the complete error message and explain, in which line the problem occurres. Then we do not have to guess the details.

It is more complicated to answer to information, which is provided in the comment section. Please collect all required information in the original question, for this reason editing the questions has been introduced in this forum.

Answer 2

[Jan]

Concerning the comment http://www.mathworks.com/matlabcentral/answers/74763#comment_147582

fapp(x) = ...

No, you cannot use x=0.8 as index. Do you want fapp(k)?