spline \*- interpolate smooth curve
takes pairs of numbers from the standard input as abcissas and ordinates
It produces a similar set, which
is approximately equally spaced and
includes the input set, on the standard output.
Numerical Methods for Engineers and Scientists,
has two continuous derivatives,
and sufficiently many points to look smooth when plotted, for
The following options are recognized,
each as a separate argument.
\fBa\fR 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.
\fBn\fR Output approximately
is given by the next argument.
\fBp\fR Make output periodic, i.e. match
First and last input values should normally agree.
\fBx\fR Next 1 (or 2) arguments are lower (and upper) \fIx\fR limits.
A limit of 1000 input points is enforced silently.