Description Usage Arguments Value Author(s) See Also Examples
From a "conreg"
object representing a linear
spline,
interpSplineCon()
produces the corresponding (cubic)
spline (via package splines' interpSpline()
)
by interpolating at the knots, thus “smoothing the kinks”.
isIsplineCon()
determines if the spline fulfills the
same convexity / concavity constraints as the underlying
"conreg"
object.
1 2  interpSplineCon(object, ...)
isIsplineCon(object, isp, ...)

object 
an R object as resulting from 
isp 
optionally, the result of 
... 
optional further arguments passed to

interpSplineCon()
returns the
interpSpline()
interpolation spline object.
isIsplineCon()
is TRUE
(or FALSE
),
indicating if the convexity/concavity constraints are fulfilled (in
knot intervals).
Martin Maechler
1 2 3 4 5 6 7 8 9 10 11 12 13  cc < conreg(cars[,"speed"], cars[,"dist"], convex=TRUE)
iS < interpSplineCon(cc)
(isC < isIsplineCon(cc)) # FALSE: not strictly convex
## Passing the interpolation spline  if you have it anyway 
## is more efficient (faster) :
stopifnot(identical(isC,
isIsplineCon(cc, isp = iS)))
## the interpolation spline is not quite convex:
plot(cc)
with(cars, points(dist ~ speed, col = adjustcolor(1, 1/2)))
lines(predict(iS, seq(1,28, by=1/4)),
col = adjustcolor("forest green", 3/4), lwd=2)

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