Re: [Gnuplot-py-users] gnuplot.py plotting wrong numbers?

[Michael H. <mh...@al...>]

Xaver Wurzenberger wrote:
> I am trying to plot large negative numbers, with 9 digits after the .,  via 
> python (version 2.5.2-3) and python-gnuplot, version 1.8-1 (both Debian Sid 
> packages), on terminal 'dumb', so ascii output.
> But it occurs to me that whenever I plot them from a (float or string) python 
> list (g.plot(Gnuplot.Data(list)), gnuplot is plotting a wrong number. 
> [...]
> 
> list_scf[0][1] is -902.904164954

The Gnuplot.py library uses float (i.e., single-precision) arrays to
store values internally.  When your value is rounded to
single-precision, it results in the number that is actually plotted.

IIRC you can get around this by passing a numpy double array to the
plot() method; I think that the library leaves the values as double
precision in this case.

Michael