Why is this matrix instantly forming in the middle of the for loop?

pi_c    =   [2 3 5 10 20 30];
M_0     =   0.1:0.1:3;

for i = 1:length(M_0)
    
    tau_r       =   1+(gamma-1)*M_0(i)^2/2;
    
    for j = 1:length(pi_c)
        
    tau_c           =   pi_c(j)^((gamma-1)/gamma);
    tau_t           =   1-(tau_r/tau_lambda)*(tau_c-1);
    S_2             =   c_p*T_0*g_c*(tau_lambda-tau_r*tau_c)./(a_0*h_PR*...
                            (sqrt(2*tau_lambda*(tau_r*tau_c*tau_t-1)/...
                                ((gamma-1)*tau_r*tau_c))-M_0));
    S_2_vec(i,j)    =   S_2*10^6;
        
    end
    
end

When I run the program I get this error:

Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

Error in HW4 (line 120)

S_2_vec(i,j) = S_2*10^6;

When I step through the program, the first time it calculates S_2, it instantly forms a 1x30 matrix, rather than just calculating one value for that iteration.

Any help would be greatly appreciated.

All the variables are shown below, the only 1x30 matrix is M_0

[meghannmarie]

One of the variables used to calculate S_2 must be a matrix (probably a 1x30 matrix). You even use the dot operator for the division leading me to believe one of these is a matrix.

This is hard to troubleshoot without some sample data for all those unknown variables.

Answer 1

[meghannmarie]

When you calculate S_2, M_0 is subtracted in last part of the equation making it a 1x30 matrix. Should you be subtracting M_0(i)?

S_2 = c_p* ...other stuff in calculation... - M_0(i)))

[Joseph Zvonek]

That was it, completely missed that, thank you!