How do I circularly shift the alphabet without using circshift function?

I'm trying to write a function that inputs the alphabet then shifts it by 3 so that then the original would be ABC...XYZ and then with the shift it'd look like XYZ...UVW.

Thanks for the help!

___________

Ok I typed this into matlab and it worked. I tried it again for a message that I want to shift 12 letters over, but it won't work.

lets say for example my message was: I HATE MATLAB.

How would i do a function so that the spaces and the punctuation would stay the same, but the message would then read: U TMFQ YMFXMN.

thanks again!

Answer 1

[Anand]

alphabet = 97 : 122;
>> char(alphabet)

ans =

abcdefghijklmnopqrstuvwxyz

shifted_alphabet = alphabet-3;
shifted_alphabet(1:3) = alphabet(end-2:end);
>> char(shifted_alphabet)

ans =

xyzabcdefghijklmnopqrstuvw

Answer 2

[Azzi Abdelmalek]

s='A':'Z';
s=[s(end-2:end) s(1:end-3)]

Answer 3

[Azzi Abdelmalek]

shiftn=12
s='A':'Z';
str='I HATE MATLAB'
idx=regexp(str,'[A-Z]')
for k=idx
  a=strfind(s,str(k))
  str(k)=s(mod(a+shiftn,26))
end

%or

shiftn=12
str='I HATE MATLAB'
sth=double(str)-64
idx=regexp(str,'[A-Z]')
sth(idx)=mod(sth(idx)+shiftn,26)
out=char(sth+64)