pwiselinterp <- function ( x, y )

#*****************************************************************************80
#
## pwiselinterp carries out piecewise linear interpolation.
#
#  Licensing:
#
#    Copyright 2016 James P. Howard, II
#
#    The computer code and data files on this web page are distributed under
#    https://opensource.org/licenses/BSD-2-Clause, the BSD-2-Clause license.
#
#  Modified:
#
#    22 February 2020
#
#  Author:
#
#    Original R code by James Howard;
#    Modifications by John Burkardt.
#
#  Reference:
#
#    James Howard,
#    Computational Methods for Numerical Analysis with R,
#    CRC Press, 2017,
#    ISBN13: 978-1-4987-2363-3.
#
{
  source ( "/home/burkardt/public_html/r_src/linterp/linterp.R" )

  n <- length ( x ) - 1
  y <- y[ order(x) ]
  x <- x[ order(x) ]

  mvec = c()
  bvec = c()

  for ( i in 1 : n )
  {
    p <- linterp ( x[i], y[i], x[i+1], y[i+1] )
    mvec <- c ( mvec, p[2] )
    bvec <- c ( bvec, p[1] )
  }

  return ( list ( m = mvec, b = bvec ) )
}