usr/man/cat1/spline.0



SPLINE(1G)          UNIX Programmer's Manual           SPLINE(1G)


N\bNA\bAM\bME\bE
     spline - interpolate smooth curve

S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
     s\bsp\bpl\bli\bin\bne\be [ option ] ...

D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
     _\bS_\bp_\bl_\bi_\bn_\be 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, _\bN_\bu_\bm_\be_\br_\bi_\bc_\ba_\bl _\bM_\be_\bt_\bh_\bo_\bd_\bs _\bf_\bo_\br _\bS_\bc_\bi_\be_\bn_\bt_\bi_\bs_\bt_\bs _\ba_\bn_\bd
     _\bE_\bn_\bg_\bi_\bn_\be_\be_\br_\bs, 2nd ed., 349ff) has two continuous derivatives,
     and sufficiently many points to look smooth when plotted,
     for example by _\bg_\br_\ba_\bp_\bh(1G).

     The following options are recognized, each as a separate
     argument.

     -\b-a\ba   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.

     -\b-k\bk   The constant _\bk used in the boundary value computation


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


          is set by the next argument.  By default _\bk = 0.

     -\b-n\bn   Space output points so that approximately _\bn intervals
          occur between the lower and upper _\bx limits.  (Default _\bn
          = 100.)

     -\b-p\bp   Make output periodic, i.e. match derivatives at ends.
          First and last input values should normally agree.

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

S\bSE\bEE\bE A\bAL\bLS\bSO\bO
     graph(1G), plot(1G)

D\bDI\bIA\bAG\bGN\bNO\bOS\bST\bTI\bIC\bCS\bS
     When data is not strictly monotone in _\bx, _\bs_\bp_\bl_\bi_\bn_\be reproduces
     the input without interpolating extra points.

B\bBU\bUG\bGS\bS
     A limit of 1000 input points is enforced silently.


Printed 7/9/88           April 29, 1985                         1