spline(1)

NAME

     spline - interpolate smooth curve

SYNOPSIS

     spline [-aknpx] ...

DESCRIPTION

     spline takes pairs of numbers from  the  standard  input  as
     abcissas  and ordinates of a function. It produces a similar
     set, which is approximately equally spaced and includes  the
     input  set,  on the standard output. The cubic spline output
     (R.  W.  Hamming,  Numerical  Methods  for  Scientists   and
     Engineers,2nd  ed.,  349ff)  has two continuous derivatives,
     and sufficiently many points to look  smooth  when  plotted,
     for example by graph(1).

OPTIONS

     -a    Supply abscissas automatically (they are missing  from
           the  input); spacing is given by the next argument, or
           is assumed to be 1 if next argument is not a number.

     -k    The constant k used in the boundary value computation

           (2nd deriv. at end) = k*(2nd deriv. next to end)

           is set by the next argument. By default k = 0.

     -n    Space output points so that approximately n  intervals
           occur  between the lower and upper x limits.  (Default
           n = 100.)

     -p    Make output periodic, that is,  match  derivatives  at
           ends.  First  and  last  input  values should normally
           agree.

     -x    Next 1 (or 2) arguments are lower (and upper)  x  lim-
           its.   Normally  these  limits are calculated from the
           data. Automatic abcissas start at lower limit (default
           0).

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWesu                     |
    |_____________________________|_____________________________|

SEE ALSO

     graph(1), attributes(5)

     R.  W.  Hamming,  Numerical  Methods  for   Scientists   and
     Engineers, 2nd ed.

DIAGNOSTICS

     When data is not strictly monotonic in x, spline  reproduces
     the input without interpolating extra points.

BUGS

     A limit of 1000 input points is enforced silently.