How to plot a 2D graph using all the for loop values

Hi, I have the following equation to be plotted in Matlab:

***************
alp=1;
K=1;
E0=1;

for w=-20:1:20;

a=K*(cos(pi*alp/2)*w^alp+w^(2*alp));
b=1+2*(cos(pi*alp/2)*w^alp+w^(2*alp));
c=a/b;
E(w)=E0*(1+c);
end

figure(1)
plot(E,w)
xlabel('w');
ylabel('E');
title('Plot of E vs w')
*********

Can anyone tell me what is wrong in the above code, as I am unable to get the plot.

Thanking You!

[Anders Kipp]

great help

Answer 1

[Azzi Abdelmalek]

Your errors:

1. you can not use a negative index
2. when you write for w=-20:20, at the end of the loop w=20, is just one value
3. you should use plot (w,E) instead of plot(E,w)

alp=1;
K=1;
E0=1;
E=[];
for w=-20:1:20;
  a=K*(cos(pi*alp/2)*w^alp+w^(2*alp));
  b=1+2*(cos(pi*alp/2)*w^alp+w^(2*alp));
  c=a/b;

    E(end+1)=E0*(1+c);
end
figure(1)
w=-20:20
plot(w,E)
xlabel('w');
ylabel('E');
title('Plot of E vs w')t(E,w)

[Pranjal Pathak]

Thanks a lot Azzi! This was what I was looking for. I have a similar problem which I have posted yesterday. Can you help me here: http://www.mathworks.com/matlabcentral/answers/81191-how-to-plot-using-all-the-for-loop-values