selfStart
model evaluates the logistic
function and its gradient. It has an initial
attribute that
creates initial estimates of the parameters Asym
,
xmid
, and scal
.
SSlogis(input, Asym, xmid, scal)
x
value at the
inflection point of the curve. The value of SSlogis
will be
Asym/2
at xmid
.input
axis.input
. It is the value of
the expression Asym/(1+exp((xmid-input)/scal))
. If all of
the arguments Asym
, xmid
, and scal
are
names of objects the gradient matrix with respect to these names is attached as
an attribute named gradient
.
nls
, selfStart