Get left and right side argument trying to execute this code, any suggestions on how to fix it?

close all; 
clear all;
 % Material Properties of Boron/Epoxy composite
 E1 = 30*10^6;
 E2 = 3*10^6;
 G12 = 1*10^6;
 v12 = .3;
 v21 = v12*(E2/E1);
 % setting the zeros for the functions
 figure
 hold on;
 theta = linspace(0,90,18);
 Ex = zeros(size(theta));
 Gxy = zeros(size(theta));
 vxy = zeros(size(theta));
 nxyx = zeros(size(theta));
 % defining the functions
 for i=1: length(theta)
 theta(i)
 [Ex(i)] = Ex_lon(E1,E2,G12,v12,theta(i));
 [Gxy(i)] = Gxy_lon(E1,E2,G12,v12,theta(i));
 [vxy(i)] = vxy_lon(Ex E1,E2,G12,v12,theta(i));
 [nxyx(i)] = nxyx_lon(Ex E1,E2,G12,v12,theta(i));
 end 
% generating the plot
 plot(theta,Ex/E2,'-+r',theta,Gxy/G12,'-*g',theta,vxy,'-^b',theta,nxyx,'-xk');
 xlabel('\theta (degree)');
 yyaxis left;
 ylabel('E_x/E_2, Gxy/G12, -nxyx');
 yyaxis right;
 ylabel('vxy');
 legend('E_x/E_2','Gxy/G12','vxy','-nxyx');
 hold off 
% the following are the functions that the previously defined functions are
 % called to
 function [Ex] = Ex_lon(E1,E2,G12,v12,theta)
 E_inv = (1/E1)*(cosd(theta)^4) + (1/G12- 2*v12/E1)*(sind(theta)^2)*(cosd(theta)^2) + (1/E2)*(sind(theta)^4);
 Ex = (1/E_inv);
 end
 function [Gxy] = Gxy_lon(E1,E2,G12,v12,theta)
 Gxy_inv = 2*(2/E1 + 2/E2 + 4*v12/E1 - 1/G12)*(sind(theta)^2)*(cosd(theta)^2)+ 1/G12*((sind(theta)^4)+(cosd(theta)^4)); 
Gxy = 1/Gxy_inv;
 end
 function [vxy] = vxy_lon(Ex,E1,E2,G12,v12,theta)
 vxy = Ex*(v12/E1 * (sind(theta)^4)*(cosd(theta)^4)-(1/E1 + 1/E2 - 1/G12)*(sind(theta)^2)*(cosd(theta)^2));
 end
function [nxyx] = nxyx_lon(Ex E1,E2,G12,v12,theta)
 nxyx = Ex*((2/E1 + 2/E2 - 1/G12)*(sind(theta))*(cosd(theta)^3)-(2/E2 +2*v12/E1 - 1/G12)*(sind(theta)^3)*(cosd(theta)));
end

[KALYAN ACHARJYA]

There is the issue as the all output arguments of different function are vectors, you are trying to save all those output arguments in array???

for i=1:length(theta)
    Ex(i)=Ex_lon(E1,E2,G12,v12,theta(i));
    Gxy(i)=Gxy_lon(E1,E2,G12,v12,theta(i));
    vxy(i)=vxy_lon(Ex,E1,E2,G12,v12,theta(i)); 
    nxyx(i)=nxyx_lon(Ex,E1,E2,G12,v12,theta(i));
end

Also note on "./" vector dot operation.

[Walter Roberson]

Yes, vxy_lon passes the vector Ex in and uses the entire vector. Perhaps it should only be passing Ex(i) in; likewise on the next line.

[Kevin Harnett]

Yes these are macro mechanical equations for materials meant to be plotted together on one plot to compare the plots. With Ex removed from the vx and nxy,x functions, the program runs perfectly but the plots are obviously not correct for those two.

[Kevin Harnett]

I tried ./ notation it still returned an error.

[Kevin Harnett]

Got it gentlemen, thank you for the help. Definitely led me in the correct direction.

[darova]

[Walter Roberson]

No Answer was created, so none can be accepted.