MATLAB: How, using a for loop, can I create an array

creating arrayfor loopplottingsimulink

I am trying to create an array for V and A that can then be plotted.
for a = [.25:.25:4] %innder radius
b = a+2 ;%outer radius
V = (.25*pi^2).*(a+b)*(b-a).^2 %equation for Volume
A = pi^2*(b^2-a.^2) %equation for Area
end
plot(V,A) %plot Volume vs. Area
with the current code, when I run the script, V and A only have one value which is equal to using a = 4
but I want every value to be saved, not just the last value for V and A

Best Answer

how using a for loop
V and A are overwritten for every iteration of the loop. Try this 
vec = [.25:.25:4];
len = length( vec );
A = nan( len, 1 );
V = nan( len, 1 );
for jj = 1 :  len
    a = vec(jj);
    V(jj) = (.25*pi^2).*(a+b)*(b-a).^2 %equation for Volume
    A(jj) = pi^2*(b^2-a.^2) %equation for Area
end
plot(V,A) %plot Volume vs. Area
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