MATLAB: Index exceeds the number of array elements

arrayMATLABxsteam

Hello,
I am trying to extract data from Xsteam.I am trying to retrive data with respect to temperature. the code is as follows. 
p = 10;
a = 1000;
b = 0.1;
rho_s = zeros(1,((a-1)/b));
L = length(rho_s);
for i = 1:L
    T(i)= 1+b*i;
    rho_s(i) =XSteam('rho_pT', p, T(i));
    
    drho_s_dT = (rho_s(i+1)-rho_s(i))/(T(i+1)-T(i));
   
end
when i run this code I am getting an error as "Index exceeds the number of array elements". Can some one check and help me how can I do this.

Best Answer

It seems that you are trying to find a derivative of rho_s w.r.t. T, you can use gradient() function
p = 10;
a = 1000;
b = 0.1;
rho_s = zeros(1,((a-1)/b));
L = length(rho_s);
T = zeros(1, L);
for i = 1:L
    T(i)= 1+b*i;
    rho_s(i) =XSteam('rho_pT', p, T(i));
end
drho_s_dT = gradient(rho_s, T);
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