stem_1=function(t,y,parms) { # # Transfer dependent variable vector to problem variables G=y[1]; P=y[2]; # # Stem cell model ODEs dGdt=a1*G^n/(tha1^n+G^n)+b1*thb1^m/(thb1^m+G^m*P^m)-k1*G; dPdt=a2*P^n/(tha2^n+P^n)+b2*thb2^m/(thb2^m+G^m*P^m)-k2*P; # # Increment calls to neuron_1 ncall <<- ncall+1; # # Return numerical derivative vector dGPdt <<- c(dGdt,dPdt); # # Return derivative vector as list return(list(c(dGdt,dPdt))) }