MATLAB Online does not run script properly

I ran the following script (which I named draft.m) through MATLAB Online:

clear;
fun = @(x, b) (b-7)*(b+5)*x.^2-2*x+3;
brange = -8:0.1:10;
fmin = [];

for b = brange
end

and got the following error message:

>> draft

Error: File: draft.m Line: 6 Column: 1

At least one END is missing. The statement beginning here does not have a matching end.

But if I remove the line

fmin = [];

then it works. Did I miss something? I suppose defining an empty array shouldn't fail the for loop, should it? Thank you very much in advance for any comments that you may have.

Answer 1

[Cris LaPierre]

Code runs without error for me. I can also run it here without error. Perhaps try again? If it happens again, perhaps there are more details you can share about what you are doing?

clear;
fun = @(x, b) (b-7)*(b+5)*x.^2-2*x+3;
brange = -8:0.1:10;
fmin = [];

for b = brange
end

b

b = 10

[Kiam Heong Kwa]

The following is the complete code:

fun = @(x,b) (b - 7)*(b + 5)*x.^2 - 2*x + 3;
brange = -8:.01:10;
fmin = [];

for b = brange
    f = @(x) fun(x, b);
    [crit, fval] = fminbnd(f, -6, 6);
    fmin(end + 1) = fval;
end

plot(brange, fmin);
xlabel('b'); ylabel('m(b)'); title('The graph of m(b)');

I am plotting the minima of the parametrized functions (given by fun and f in the code) versus b. I am pretty sure it should work -- I ran the code before and I also tried it on GNU Octave just now. Here's the plot from the latter:

I am really not sure what's happening with my MATLAB Online and hence I posted the question.

Any clues?

Thanks.

[Kiam Heong Kwa]

By the way, if it helps, I am using MATLAB Online through Firefox 100.0 (64-bit) on macOS Big Sur.

Thanks again.

[Torsten]

And the error message is the one you posted above:

Error: File: draft.m Line: 6 Column: 1

At least one END is missing. The statement beginning here does not have a matching end.

?

[Kiam Heong Kwa]

Yes, in both cases -- with the incomplete and the complete codes. And here's the content of my MATLAB drive:

>> ls

calc_roots.m draft.m factorial2.m funxy.m matlab_logo.jpg prob2.m square.m

dist2.m Euler fig3_4_2.png g.m my_dfact.m Published stats_2.m

draft.asv Exam friendship_paradox.mlx Martinez prob1.m Shared test_dist2.m

whch I don't see any conflicts with the script -- or maybe I missed something?

Thank you very much.

[Torsten]

Just a guess:

What if you use

fmin = [fmin,fval];

instead of

fmin(end+1) = fval;

or even better:

fmin = zeros(numel(brange),1)
for b = brange
    f = @(x) fun(x, b);
    [crit, fval] = fminbnd(f, -6, 6);
    fmin(b) = fval;
end

[Kiam Heong Kwa]

It ended up with the same error message. In fact, in the incomplete version of the code, neither of the statements is within the loop and code still failed to work. And, I assume

fmin(end+1) = fval;

is syntatically correct?

Confusing indeed. Once in a while having fun with bizzarre behavior of our machines. Hehe.

[Cris LaPierre]

The full code runs fine for me.

Try resetting your MATLAB Online session.

[Kiam Heong Kwa]

This helps! Thanks a lot!

Take care.