James McDermott wrote:
Would the unique quadratic defined by the three points be the same
curve as the curve predicted by a quadratic B-spline (fit to all of
the data) through those same three points?
Yes, if you restrict attention to an interval between knots. You'll
need to re-evaluate it
Thanks a lot for the input on this Professor Murdoch. I really
appreciate all the help.
Regards,
Jim
On 7/20/05, Duncan Murdoch [EMAIL PROTECTED] wrote:
James McDermott wrote:
Would the unique quadratic defined by the three points be the same
curve as the curve predicted by a quadratic
Hello,
I have been trying to take the derivative of a quadratic B-spline
obtained by using the COBS library. What I would like to do is
similar to what one can do by using
fit-smooth.spline(cdf)
xx-seq(-10,10,.1)
predict(fit, xx, deriv = 1)
The goal is to fit the spline to data that is
On 7/19/2005 2:53 PM, James McDermott wrote:
Hello,
I have been trying to take the derivative of a quadratic B-spline
obtained by using the COBS library. What I would like to do is
similar to what one can do by using
fit-smooth.spline(cdf)
xx-seq(-10,10,.1)
predict(fit, xx, deriv = 1)
I wish it were that simple (perhaps it is and I am just not seeing
it). The output from cobs( ) includes the B-spline coefficients and
the knots. These coefficients are not the same as the a, b, and c
coefficients in a quadratic polynomial. Rather, they are the
coefficients of the quadratic
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of James McDermott
Sent: Tuesday, July 19, 2005 2:54 PM
To: r-help@stat.math.ethz.ch
Subject: [R] Taking the derivative of a quadratic B-spline
Hello,
I have been trying to take the derivative of a quadratic B
On 7/19/2005 3:34 PM, James McDermott wrote:
I wish it were that simple (perhaps it is and I am just not seeing
it). The output from cobs( ) includes the B-spline coefficients and
the knots. These coefficients are not the same as the a, b, and c
coefficients in a quadratic polynomial.
Would the unique quadratic defined by the three points be the same
curve as the curve predicted by a quadratic B-spline (fit to all of
the data) through those same three points?
Jim
On 7/19/05, Duncan Murdoch [EMAIL PROTECTED] wrote:
On 7/19/2005 3:34 PM, James McDermott wrote:
I wish it were
