psi: add support to compute the polygamma function (kth-derivative). * libinterp/corefcn/psi.cc: previously, only the digamma function, k == 0, was being computed. Add support for polygamma function, add tests, and improve documentation. * liboctave/cruft/slatec-fn/dpsifn.f, liboctave/cruft/slatec-fn/psifn.f: the two functions that actually compute the the polygamma functions, copied verbatim from SLATEC, and under public domain. * liboctave/cruft/slatec-fn/module.mk: add dpsifn.f and psifn.f to the build system. * liboctave/numeric/lo-specfun.cc: add new signature for function psi to compute polygamma function that wraps the Fortran DPSIFN and PSIFN functions. * liboctave/numeric/lo-specfun.h: declare new function and document all psi() with doxygen.

#! /bin/sh

set -e
GREP=${GREP:-grep}
SED=${SED:-sed}

srcdir="$1"
shift

for arg
do
  if [ -f "$arg" ]; then
    file="$arg"
  else
    file="$srcdir/$arg"
  fi
  if [ "`$GREP -l '^%!' $file`" ]; then
    echo "$file" | $SED "s,\\$srcdir/,,";
  fi
done