linterp <- function ( x1, y1, x2, y2 )

#*****************************************************************************80
#
## linterp computes the intercept and slope of a line.
#
#  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:
#
#    20 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.
#
{
  m <- ( y2 - y1 ) / ( x2 - x1 )
  b <- y2 - m * x2

  return ( c ( b, m ) )
}