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R can generate a spline function using splinefun() in the splines library. However, I need to evaluate this function at its first and second derivatives. Is there a way to do this?
for example
library(splines)
x <- 1:10
y <- sin(pi/x) #just an example
f_of_x <- splinefun(x,y)
How can I evaluate f'(x) for a vector of x's?
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Split() is a built-in R function that divides a vector or data frame into groups according to the function's parameters. It takes a vector or data frame as an argument and divides the information into groups.
In the mathematical field of numerical analysis, spline interpolation is a form of interpolation where the interpolant is a special type of piecewise polynomial called a spline.
Cubic regression spline is a form of generalized linear models in regression analysis. Also known as B-spline, it is supported by a series of interior basis functions on the interval with chosen knots. Cubic regression splines are widely used on modeling nonlinear data and interaction between variables.
The spline has four parameters on each of the K+1 regions minus three constraints for each knot, resulting in a K+4 degrees of freedom.
It is very easy to do since the ability to evaluate the function at its derivatives is built in to the function!
f_of_x(x, deriv = 1)
Thanks R-core!
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You may also be interested in the TkSpline function in the TeachingDemos package which will plot the spline function along with its derivatives.
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