# I am trying to plot the each value of C at different theta values, but I found an error. Error: Invalid expression. When calling a function or indexing a variable, use parenth

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clear all

clc

c=[0.5,0.75,1,1.1];

theta=[-pi:0.01:pi];

a=zeros(1,629);

for k=c

G(k)=(1+4*(a(k)).^2-a(k)).*(sin(theta/2)).^2);

plot(G(k),theta);

end

##### 3 Comments

Walter Roberson
on 5 Dec 2022

### Answers (2)

Alan Stevens
on 5 Dec 2022

Do you want something more along the following lines?

c=[0.5,0.75,1,1.1];

theta=-pi:0.01:pi;

%a=zeros(1,629);

for k=1:numel(c) % numel is number of elements in c

% There are four values of c and all the a's are zero

% so I've replaced a by c in the following.

G(k,:)=(1+4*c(k).^2-c(k)).*sin(theta/2).^2;

end

plot(theta,G);

xlabel('\theta'), ylabel('G')

##### 0 Comments

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