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spline(1)                        User Commands                       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  approxi-
       mately  equally spaced and includes the input set, on the standard out-
       put. The cubic spline output (R. W. Hamming, Numerical Methods for Sci-
       entists  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 limits.  Nor-
                mally these limits are calculated  from  the  data.  Automatic
                abcissas start at lower limit (default 0).



ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:


       tab()     allbox;     cw(2.750000i)|    cw(2.750000i)    lw(2.750000i)|
       lw(2.750000i).  ATTRIBUTE TYPEATTRIBUTE VALUE AvailabilitySUNWesu


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.



SunOS 5.10                        14 Sep 1992                        spline(1)