binary lookup

[Jaroslav Hajek]

hello,

please consider applying the attached changeset. It implements a
generic sequential binary lookup (optimized for dense downsampling)
in liboctave/oct-lookup.h and wraps it in src/DLD-FUNCTIONS/lookup.cc
instead of the current scripts/general/lookup.m which is implemented
using sort. Also, the new lookup can search cell arrays of strings.
At least one more DEFUN can benefit from including the algorithm in
liboctave: DLD-FUNCTIONS/__lin_interpn__.cc. This is not part of this
changeset - I'll create it later if this one is accepted.

Also attached is the benchmark script I've used last time. With the
improved sort the results are less impressive; still, in the optimized
"dense downsampling" case there is an order of magnitude performance
improvement (at least on my system).


-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz
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