MATLAB: Storing decimal numbers in for loop: getting a single vector

for loop

I want to store decimal numbers in the for loop.
for e = 0:0.1:1
    k = sqrt(2.*e);
    q = sqrt(2.*(e+(V0./2)));
    r = sqrt (2.*(e+V0));
    a = ((r+q+(2.*s1.*lambda)).*(k+q+(2.*s1.*lambda)).*expm(s1.*(r-q).*0.48)) - ((r-q+          (2.*s1.*lambda)).*(k-q+2.*s1.*lambda).*expm(s1.*(r+q).*0.48)); 
    Trans = (4.*k.*q)./a;
    wfn = Trans.*conj(Trans);
    posit1(e,1) = e;
    wfn1(e,1) = wfn;
 end
 plot( posit1, wfn1);
I want to store all the values from 0 to 1 with an interval of 0.1 Please help me how to do it??

Best Answer

Parikshit, you cannot use non-integer indices (such as 0.1) to access or write to a matrix. Also, indexing in MATLAB starts with 1, not 0. Instead, use
...
e = 0:0.l:1;
for ii = 1:length(e)
   k          = sqrt(2.*e(ii));
   q          = sqrt(2.*(e(ii)+(V0./2)));
   r          = sqrt(2.*(e(ii)+V0));
   a = ((r+q+(2.*s1.*lambda)).*(k+q+(2.*s1.*lambda)).*expm(s1.*(r-q).*0.48)) - ((r-q+          (2.*s1.*lambda)).*(k-q+2.*s1.*lambda).*expm(s1.*(r+q).*0.48)); 
   Trans      = (4.*k.*q)./a;
   wfn        = Trans.*conj(Trans);
   posit1(ii) = e(ii);
   wfn1(ii)   = wfn;
end
Some other suggestions:
  • Instead of accessing e(ii) time and again in the loop, you could do a e_ii = e(ii) as the first line in the loop, and then use e_ii throughout the loop.
  • Especially for large matrices you would want to pre-allocate. That is, put
 posit1 = zeros(length(e),1);
 wfn1   = zeros(length(e),1);
in front of the for-command.
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