Hill Equation coding

Hi,

I am having trouble coding for the Hill Equation. I have written the code but when I try to code for equation B, the error message that pops up is: ??? Subscript indices must either be real positive integers or logicals.

Error in ==> practice1 at 13 B = A + Kd(k) * (1+ (sum ((factorial (k)/(factorial (k-i)*factorial (i)))/(prod(Kd*j))))) %part of equation for Q

Here is my code thus far:

sum = 0; %initialize sum Kd = 4; %dissociation constant - input k = 1; %Hill coefficient i = 1; %needed for calculation of sum j = 1; %needed for calculation of prod

for L = (1:5); %for Ligand concentration from 1 to 5 micro-Molar

    A = (L).^k / prod(Kd) %part of equation for Q
    B = A + Kd(k) * (1+ (sum ((factorial (k)/(factorial (k-i)*factorial (i)))/(prod(Kd*j))))) %part of equation for Q
    Q(L) = A/B  %A over B equals Bound receptor-ligands over Total Receptors

end %end loop

figure (1) %1st figure plot (Q) %plot Q vs L ... Bound/Total vs Ligand Concentration

-- I understand that I am doing something wrong with the SUM part of the equation, but I don tunderstand how to fix it. Any help will be much appreciated! Thank you!

Answer 1

[Poonam]

we got the sum function to work by doing this:

for L = (1:200); %for Ligand concentration from 1 to 200 micro-Molar

    A = (L).^k / prod(Kd); %part of equation for Q
    f =  (factorial (k)/(factorial (k-i)*factorial (i)))/(prod(Kd*j)); % portion of equation for B
    sum = sum + f;  % sum equals sum plus f to be part of equation B
    B = A + Kd(k) * (1 + sum);  %portion of equation for Q
    Q(L) = A/B;  %A over B equals Bound receptor-ligands over Total Receptors

end %end loop

can anyone tell me if this is the correct way to do it?