Inferring the divergence rate between orthologs as a function of divergence time or protein distance

Define t and y vectors to fit divergence model. For each pair of orthologs, values in t are the divergence time between species expressed in billions of years, values in y are the percent sequence identity between corresponding orthologs.
Use the fitnlm function in matlab (or an alternative nonlinear regression method) to fit equation 3 from Konate et al. and retrieve the values for the R₀ and alpha parameters. (relevant matlab code shown below).
model3=@(b,x)100.*((b(1).*x/b(2))+1).^-b(2)
beta=[1,0.5];
fit=fitnlm(t,y,model3,beta);
[R0,alpha]=fit.Coefficients.Estimate;
Use the obtained R₀ and alpha parameters in equation 5 from Konate et al. to determine the divergence rate (dy/dt) at an arbitrary t expressed in billions of years.
Alternatively, use the obtained R₀ and alpha parameters in equation 4 from Konate et al. to determine the divergence rate an arbitrary protein distance expressed as a fraction (i.e. 1 – percent identity/100)