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aspline - Akima spline interpolation

aspline[-axstep] [-lllim] [-uulim] [-nn] {file(s)}

asplinereads pairs of numbers from the indicatedfile(s)(or from stdin if no files were given) as abscissas and ordinates of a function. It produces a similar set, which is approximately equally spaced and includes the input set on standard output. The output is anAkima- interpolated spline which has an continuous first derivative. The second derivate may be discontinuous, but the output does not wiggle as it would do with cubic splines. Datasets are separated by blank lines.

-aincr,--auto=incrsupply abscissas automatically, since 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.-lllim,--llimit=llimset lower x-limit tollim,-uulim,--ulimit=ulimset upper x-limit toulim,-nn,--points=nspace output points so that approx.nintervals occur between the lower and upper limit,-vbe verbose,-hprint help message on stderr and exit.

spline(1),gnuplot(1).H.Akima,ANewMethodofInterpolationandSmoothCurveFittingBasedonLocalProcedures,JournalofAssc.forComp.Mach.,Vol.17,No.4,Oct.1970,pp.589602

If you need a continuous second derivative, usesplinefrom the plotutils package instead.