R/evlpoly.R

In fields: Tools for Spatial Data

#
# fields  is a package for analysis of spatial data written for
# the R software environment.
# Copyright (C) 2024 Colorado School of Mines
# 1500 Illinois St., Golden, CO 80401
# Contact: Douglas Nychka,  douglasnychka@gmail.com,
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with the R software environment if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
# or see http://www.r-project.org/Licenses/GPL-2
##END HEADER
fields.evlpoly <- function(x, coef) {
    # evaluates polynomial at x values with coefficients coef[i] and powers i-1
    #
    n <- length(x)
    J <- length(coef)
    results <- rep(0, n)
    temp <- .Fortran("evlpoly",PACKAGE="fields",
                     x = as.double(x),
                     n = as.integer(n), 
                     coef = as.double(coef),
                     j = as.integer(J),
                     results = as.double(results))$results
    return(temp)
}