I keep getting the error Subscript indices must either be real positive integers or logicals.

theta=linspace(-pi,pi,500); 
P=[269.2 15913 8964 2421]; 
E1=0.206; 
Nth=length(theta), NP=length(P);
r1=zeros(Nth,NP);
for i=1:Nth
c=1-(E1*cos(theta(i)));
for j=1:NP
r1=(E1*P(j))/c;
end
end

Answer 1

[Walter Roberson]

That code executes without difficulty for me. However you are overwriting all of r1 every iteration of j and every iteration of i. Perhaps you want

r1(i, j) = (E1*P(j))/c;

[Michele Thompson]

This fixed it for me thank you so much!