Re: segfault in plot3d

[James R. V. Z. <jr...@co...>]

Ethan A Merritt <merritt@u.washington.edu> writes:
>Why does your data file have two blank lines between each set of points?
>
>If you reduce that to a single blank line then there is no segfault.
>Of course, it should not segfault in any case, but I'm wondering if
>this is why no one has reported the problem before.

I used two blank lines so I could use "index" specs to select portions
of the data file for plotting, or more usefully, for fitting.

From: Daniel J Sebald <dan...@ie...>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20041020
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Ethan A Merritt <merritt@u.washington.edu>
CC:  gnu...@li..., 
 "James R. Van Zandt" <jr...@co...>
Subject: Re: segfault in plot3d
References: <E1L...@va...> <200902172152.08953.merritt@u.washington.edu>
In-Reply-To: <200902172152.08953.merritt@u.washington.edu>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-AntiAbuse: This header was added to track abuse, please include it with any abuse report
X-AntiAbuse: Primary Hostname - deneb.hostpapa.com
X-AntiAbuse: Original Domain - comcast.net
X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse: Sender Address Domain - ieee.org
X-Source: 
X-Source-Args: 
X-Source-Dir: 

Ethan A Merritt wrote:

>>gnuplot> splot 'lin2.dat',x+y
> 
> 
> Why does your data file have two blank lines between each set of points?
> 
> If you reduce that to a single blank line then there is no segfault.
> Of course, it should not segfault in any case, but I'm wondering if
> this is why no one has reported the problem before.

Daniel J Sebald <dan...@ie...> wrote:
> That explains it.  The double line break means to start another 3D
> curve.  (A single break means to start another trace of the 3D curve.)
> So Jim's example is attempting a 3D plot with single dimensioned data.

I don't follow what you mean by "single dimensioned data".  Each point
has an X, Y, and Z value.  With "set style data lines", the points are
connected along only one dimension, which is fine with me.  Actually I
was using the default style, so I got only the points.

> Either a check should be put in plot3d.c, or a datafile [like this]
> should be disallowed...

I see no reason to disallow it.  It used to work.  And it still works
unless you plot data after a function.  (Succeeds by accident?)  

The docs say

"If all datablocks contain the same number of points, gnuplot will
draw cross-isolines between datablocks, connecting corresponding
points."

Apparently gnuplot should check that there is more than one datablock
before attempting to draw cross-isolines.

          - Jim Van Zandt