```1`SPLINE(1G)                                                          SPLINE(1G)`
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```

## NAME

```6`       spline - interpolate smooth curve`
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```

## SYNOPSIS

```9`       spline [ option ] ...`
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```

## DESCRIPTION

```12`       Spline  takes  pairs of numbers from the standard input as abcissas and`
13`       ordinates of a function.  It produces a similar set, which is  approxi‐`
14`       mately  equally spaced and includes the input set, on the standard out‐`
15`       put.  The cubic spline output (R. W.  Hamming,  Numerical  Methods  for`
16`       Scientists  and  Engineers,  2nd ed., 349ff) has two continuous deriva‐`
17`       tives, and sufficiently many points to look smooth  when  plotted,  for`
18`       example by graph(1).`
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20`       The following options are recognized, each as a separate argument.`
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22`       -a   Supply  abscissas automatically (they are missing from the input);`
23`            spacing is given by the next argument, or is assumed to  be  1  if`
24`            next argument is not a number.`
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26`       -k   The constant k used in the boundary value computation`
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28`                     (2nd deriv. at end) = k*(2nd deriv. next to end)`
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30`            is set by the next argument.  By default k = 0.`
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32`       -n   Space  output  points  so  that  approximately  n  intervals occur`
33`            between the lower and upper x limits.  (Default n = 100.)`
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35`       -p   Make output periodic, i.e. match derivatives at ends.   First  and`
36`            last input values should normally agree.`
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38`       -x   Next  1 (or 2) arguments are lower (and upper) x limits.  Normally`
39`            these limits are calculated from  the  data.   Automatic  abcissas`
40`            start at lower limit (default 0).`
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```

```43`       graph(1)`
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```

## DIAGNOSTICS

```46`       When  data  is  not strictly monotone in x, spline reproduces the input`
47`       without interpolating extra points.`
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```

## BUGS

```50`       A limit of 1000 input points is enforced silently.`
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54`                                                                    SPLINE(1G)`
```