Fourier Basis Function Values
Evaluates a set of Fourier basis functions, or a derivative of these functions, at a set of arguments.
fourier(x, nbasis=n, period=span, nderiv=0)
x |
a vector of argument values at which the Fourier basis functions are to be evaluated. |
nbasis |
the number of basis functions in the Fourier basis. The first basis function is the constant function, followed by sets of sine/cosine pairs. Normally the number of basis functions will be an odd. The default number is the number of argument values. |
period |
the width of an interval over which all sine/cosine basis functions repeat themselves. The default is the difference between the largest and smallest argument values. |
nderiv |
the derivative to be evaluated. The derivative must not exceed the order. The default derivative is 0, meaning that the basis functions themselves are evaluated. |
a matrix of function values. The number of rows equals the number of arguments, and the number of columns equals the number of basis functions.
# set up a set of 11 argument values
x <- seq(0,1,0.1)
names(x) <- paste("x", 0:10, sep="")
# compute values for five Fourier basis functions
# with the default period (1) and derivative (0)
(basismat <- fourier(x, 5))
# Create a false Fourier basis, i.e., nbasis = 1
# = a constant function
fourier(x, 1)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.