On Friday 07 January 2011, David Kuehling wrote:
> >>>>> "Delbert" == Delbert Franz <[email protected]> writes:
>
> > 2. Developed an adaptive integration routine in Lua--a language I had
> > not heard of until I got the Nanonote. Lua is quite fast and small.
>
> You mean integration, as in math/numerics? Would you think the plplot
> binding for Lua would be useful for doing math stuff on the NanoNote w/
> lua?
>
> http://plplot.sourceforge.net/examples.php
> http://plplot.svn.sourceforge.net/viewvc/plplot/tags/v5_9_7/examples/lua/x01.lua?revision=11242&view=markup
>
> It might not be too difficult to add a lua binding package, however as
> somebody who doesn't use nor know Lua, I won't really able to test that
> stuff.
>
> David
>
Yes, David, as in math/numerics. The routine is based on using a
sequence of increasing order Clenshaw-Curtis rules starting with 3
points (Simpson's rule) and ending with 1025 points. I exploit the
symmetry of the rules to save storage space and also a bit of
computation. It does reasonably well when run against some published
sets of test integrals. I'm still working on a decision rule between
subdividing the interval and starting over versus continuing to
increase the order of the rule to reach the requested tolerance. Gets
a bit messy. Of course, any "real-world" numerical program gets
messy! I'm hoping to code the same algorithm in C. Lua is quite fast
but I suspect a native compiled C program would be many times faster.
However, if it doesn't work well, all a faster program does is reach
the "wrong" answers in less time. One must always keep that in mind
when trying to make software faster.
And yes, a graphical package that would work without using all the
memory of the Nanonote would be nice for Lua as well as for C and for
Python. I have looked at what used to be called "line-printer" plots,
but they are limited in what they can do and are quite "ugly".
However, with only 32MB we can't be too "snooty" can we?:-) I have
some more ideas on how to exploit ncurses using a tiny font to get
something that would be useful if not beautiful. I have turned on the
4x6 font in the kernel for the console. It is really tiny but I can
generally read it (after cataract surgery I have quite sharp near
vision with low-power glasses). This gives a 40x80 terminal which
might be OK for plotting. The ncurses howto already includes an
example plot routine that could probably be adapted.
I'm not an expert in Lua. I have looked at software written by
experts, and I can hardly follow what is going on. There are many
clever ways to use the higher-level constructs in Lua and I have
barely touched those. In general my code tends to be somewhat
"simple-minded " and straightforward. I have to get it "right" first
before I get it fast and generally when I get it right, it turns out
to be fast enough!
Delbert
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