can anyone find the bug in my 3 line code.

for n = −20:20 % Compute Fourier series coefficients

c(n + 21) = quad(@(x)(exp(sin(x).ˆ6).*exp(−1i*x*n)),0,pi,1e−4);

end

I get the following error when I run the above code

??? Error: File: D:\install\work\test\small.m Line: 1 Column: 8 Missing variable or function.

Answer 1

[Sean de Wolski]

clear
for n = -20:20 % Compute Fourier series coefficients
  c(n + 21) = quad(@(x)(exp(sin(x).^6).*exp(-1i*x*n)),0,pi,1e-4);
end

copied and pasted works on my system. You're not showing us everything.

[Neels]

thats all, i still get the same error

[Neels]

there is nothing extra in my code.

[Sean de Wolski]

Neels, copy and paste what I have above into your editor; and run it. Report the full error message.

[Neels]

??? Error: File: D:\install\work\test\small.m Line: 1 Column: 8

Missing variable or function.

[Sean de Wolski]

did you copy and paste it into a new editor window, not 'small' which has errors?

[Neels]

thanks Sean de, it doesn't give me an error. But there is also no answer. The command window just shows a prompt

[Sean de Wolski]

yes; that's expected since you have output suppressed (a good thing)

disp(c)

to view some output

[Neels]

Thanks you very much, Sean de. I get the result now. was the error because of some previously stored values in the variables?

[Sean de Wolski]

No. It's probably because of what Jan said in that you had unexpected characters (minus sign), possibly keyboard artifacts or bad copying and pasting, I'm not sure. However, I'll bet if you looked at the editor you'll see a red squiggly line under some of the characters with an mlint message "invalid characters" if you hover your mouse over it?

[Neels]

I tried it again with the old script again. I still cannot find any of the those hint of errors. any way i shall try it again. thanks

Answer 2

[Jan]

for n = −20:20
??? Error: File: D:\install\work\test\small.m
Line: 1 Column: 8 Missing variable or function.

Line 1 column 8 is a "−" (mdash), not a "-" (minus). The same problem appears in the second line. And as Sean de found out: "ˆ" is not "^".

How did you create this piece of code? Did you copy it from a PDF file?

[Sean de Wolski]

I had to change toe carrot ^ too.

[Neels]

thanks, i was just trying to test some pre-existing code in the web to check numerical integration. but still it shows the error

Answer 3

[Paulo Silva]

for n = -20:20 % Compute Fourier series coefficients

c(n + 21) = quad(@(x)(exp(sin(x).^6).*exp(-i*x*n)),0,pi,1e-4);

end

Just a few weird symbols and -1i should be just -i

[Sean de Wolski]

Paulo, on some systems, mine included, it's recommended to use 1i as the imaginary component since it won't be overwritten.

Try putting this in an editor to see if mlint tells you

clear i x

x = 3+4*i

[Neels]

thanks, but even after i change it, it shows the same error

[Paulo Silva]

Hi Sean you are correct, I never used 1i with MATLAB and it does work, we learn something new everyday, thanks