On Sun, 29 Jul 2007, j.chitte wrote:
> --- In "Ray" <> wrote:
> >
> > I am new to this list, so maybe I am missing something, but
> > what is wrong with just compiling gnuplot for your target.
> >
> > I am running debian on TS7400 just installed gnuplot it seems
> > to work fine although you have to output to a file, since I
> > have no X. (actually no video display).
> >
> > Should be ok for a web server if that's what you are doing.
> > Also since you are just visualizing some data, speed is not an
> > issue. Not like doing some compute intensive graphics..
> >
>
> thanks for your thoughts Ray.
>
> good to know gnuplot installs without issues. However if you look at
> my earlier post you'll see I'm doing more that just visualising.
>
> I have used gnuplot to do linear regression fitting of logrithmic
> calibration curves to some thermistor data. I sample several data
> channels and use the log fn on the fly to convert that resistance
> data to temperature as it's plotted. I have also pursuaded gnuplot to
> do a trapezoidal area under graph integral and plot that finally
> fitting a polynomial to the resulting data.
Sounds like the solution would be to just use the ts board for the data
capture and then do the post processing on the desktop?
>
> In fact I was amazed I could do all that with gnuplot which claims to
> do no more than plot data.
>
> This is pretty fast on the desktop machine , Athlon XP at 2.3GHz, but
> it's not instantaeous. I doubt I will be able to do the same thing
> with a larger data set from automatic sampling on a slow CPU using
> very slow software FP emulation.
>
> I was also using CVS gnuplot which may well have some dependancy
> issues with the rather "historic" feature set of the std TSlinux
> distribution.
>
>
> It appears that I would need to move to current stable Debian with a
> 2.6 kernel, this would at least give kernel fp emu and possibly even
> crunch support (if it can be limitted to using the bits that work
> ;) ). However, all this would probably be far more work that
> recoding what I've done.
>
> BTW, what version of gnuplot is it?
>
> Thx.
>
>
> > On the subject of fixed vs float wars, I am firmly on the side of
> > fixed point, although I have written my own floating point
> > libraries in assembler (many years ago). The only time you
> > **REALLY** need floating point for realtime is when a variable
> > has a very large dynamic range, and those instances are fairly
> > rare.
>
> I quite agree, but I ain't about to recode gnuplot in fixed point ;)
> I may try to recalibrate using a polynomial or dig out a series
> approx to the log function that can be done in fixed point. The
> regression fit can be done once only and can take it's time.
>
> The plotting should be pretty straighforward and could be done much
> more efficiently that using a generalised tool like gnuplot.
>
>
>
> >Nowadays it seems everything has hardware floating point
> > and as a result it becomes the easy way out.
> >
> > Meantime, try compiling something like
> >
> > float x,y,z;
> > x=123.456;
> > y=567.890;
> > z = x*y;
> > printf("z=%f\n",z);
> >
> > I would be surprised if it didn't work..... :-)
> >
> >
> > Hope this helps.
> >
> > Regards Ray
> >
> >
>
>
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