how, using a for loop, can I create an array

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George Amor
George Amor 2020-12-7
评论： George Amor 2020-12-7
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

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采纳的回答

per isakson
per isakson 2020-12-7
编辑：per isakson 2020-12-7
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

更多回答（1 个）

David Hill
David Hill 2020-12-7
编辑：David Hill 2020-12-7
No loop needed.
a=.25:.25:4;
b=a+2;
V=(.25*pi^2).*(a+b).*(b-a).^2;
A=pi^2*(b.^2-a.^2);
plot(V,A);

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