These functions provide an interpolation mechanism for objects of
class lgtdl. The AsIs method is the vectorized version.
Usage
interpprev(x, ...)
## S3 method for class 'lgtdl'
interpprev(x, time, cov, ...)
## S3 method for class 'AsIs'
interpprev(x, ...)
Arguments
x
x is either an object of class lgtdl or of
class AsIs. It is the object on which interpolation is to be
performed.
time
A vector of times at which interpolation is requested.
cov
The name of the covariate on which interpolation is
requested. It is only required if x has more than one
covariate.
...
Ignored.
Details
If objects of class lgtdl are inserted into a data frame they
become a vector with class AsIs. In order to operate on these
we provide a method for that class. The method is simply a vectorized
version.
Value
interpprev.lgtdl returns a numeric vector of the interpolated
values of the covariate at the time(s) specified by time.
interpprev.AsIs returns a vector of interpolated values of the
covariate. In this case the vector contains one value for each element
x. time must be either the same length as x or
of length one. In the latter case all interpolations are done at that
time.
providing 
.