CygWin-1.7.3-1 fails to provide pipe.
2010.04.06.11:47:29 UT
Hello CygWin folks,
I use cygwin to serve as a Win32 platform
for GNU Octave, a freeware mathematics program
that mimics the functionality of Matlab.
The octave program produces graphical
output by exporting scripts of graphing commands
to the gnuplot graphing suite. I am using the
pre-compiled octave-3.2.4 under CygWin-1.7.3-1 on
a WinXP Pro. SP3 uni-processor PC (Dell OptiPlex
GX260, 2.4 GHz, 1024 MBt RAM). My X-server is
Xorg-1.7.6-2 with the XWin window manager. This
cygwin/octave uses gnuplot-4.2-4.
The difficulty that I experienced with octave
was coming up in any instance where I called for a
plotting window. The following short octave script
does it.
<file: frst_plot.m>
xvals = [ -3.0 : 0.2 : 5.0 ] ;
wuns = ones( size( xvals ) ) ;
yvals = (-2.0)*xvals + (1.5)*wuns ;
plot( xvals, yvals, 'k-' ) ;
</file>
I received the following octave errors; though if I
executed a simple plot using only gnuplot, the new
X-window appeared and plotted in its normal fashion.
error: __gnuplot_get_var__: Can not open fifo.
error: called from:
error: /usr/share/octave/3.2.4/m/plot/__gnuplot_get_var__.m
at line 156, column 7
error: /usr/share/octave/3.2.4/m/plot/__go_draw_axes__.m
at line 39, column 18
error: /usr/share/octave/3.2.4/m/plot/__go_draw_figure__.m
at line 92, column 3
error: /usr/share/octave/3.2.4/m/plot/gnuplot_drawnow.m
at line 99, column 5
I went to the __gnuplot_get_var__.m script within
the octave suite, and looked. It seems to be precisely
what the error messages were saying: the octave could not
open a fifo pipe through which it sends its plotting
commands to gnuplot.
At the suggestion of Tatsuro Matsuoka (one of the
GNU Octave developers), I reverted from the CygWin-1.7.3-1
(that I installed yesterday) back to the CygWin-1.7.2-2.
This cleared the problem immediately.
What I am suggesting is that the new cygwin.dll has
difficulties implementing the kind of pipe that octave
uses to send its graphing commands to gnuplot. The
specific details of the pipe that serves as an example
of this can be seen in the __gnuplot_get_var__.m script
inside the GNU Octave package.
Thank you,
George gbarr...@walsh.edu
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