For Loop is only running once

My for loop is only running one time and M_Star2 and M_Star should be a 1x41 matrix but it only comes out as one number. Here is my code: Solution??

clc
clear workspace

gamma = 1.4;
M = 3:0.1:7;

for ii = 1:size(M);
   P_staticRATIO = 1 + (2*gamma/gamma+1)*((M.^2)-1);
   P_stagRATIO = (((((gamma+1)^2)*M.^2)/(4*gamma.*(M.^2))-2*(gamma-1)).^3.5)*(((-.4)+2*gamma.*M.^2)/2.4);
   M_star2 = ((gamma+1).*M.^2)/(2+(gamma-1).*M.^2);
   M_star = sqrt(M_star2);
   plot(P_staticRATIO,P_stagRATIO,P_staticRATIO,M_star);
   legend('Stagnation Pressure Ratio','M*')
   title('M* & Stagnation Pressure Ratio as a Funciton of Static Pressure Ratio')
   xlabel('Static Pressure Ratio')
   ylabel('M*, Stag. Pressure Ratio')
end

Answer 1

[aara]

the size function returns a vector [1 41] which is why the loop only runs once.

Use:

for ii = 1:max(size(M));