| SSmicmen {stats} | R Documentation |
This selfStart model evaluates the Michaelis-Menten model and
its gradient. It has an initial attribute that
will evaluate initial estimates of the parameters Vm and K
SSmicmen(input, Vm, K)
input |
a numeric vector of values at which to evaluate the model. |
Vm |
a numeric parameter representing the maximum value of the response. |
K |
a numeric parameter representing the input value at
which half the maximum response is attained. In the field of enzyme
kinetics this is called the Michaelis parameter. |
a numeric vector of the same length as input. It is the value of
the expression Vm*input/(K+input). If both
the arguments Vm and K are
names of objects, the gradient matrix with respect to these names is
attached as an attribute named gradient.
Jose Pinheiro and Douglas Bates
PurTrt <- Puromycin[ Puromycin$state == "treated", ]
SSmicmen( PurTrt$conc, 200, 0.05 ) # response only
Vm <- 200; K <- 0.05
SSmicmen( PurTrt$conc, Vm, K ) # response and gradient
getInitial(rate ~ SSmicmen(conc, Vm, K), data = PurTrt)
## Initial values are in fact the converged values
fm1 <- nls(rate ~ SSmicmen(conc, Vm, K), data = PurTrt)
summary( fm1 )
## Alternative call using the subset argument
fm2 <- nls(rate ~ SSmicmen(conc, Vm, K), data = Puromycin,
subset = state == "treated")
summary(fm2)