With the the changes to plbuf that need to be made to implement these features, 
should the old code that was left in (the ifdef BUFFERED_FILE blocks) be 
removed?  The only time it is useful is on low memory machines that have the 
ability to perform file I/O. 

I'm not clear on the need to prefix the commands with the size. With the 
version number there is sufficient information to use the appropriate parser. 

I can make the changes described by Phil. Should I pull the current released 
version from the repository?



> On Jan 12, 2015, at 10:10 AM, Phil Rosenberg <p.d.rosenb...@gmail.com> wrote:
> 
> Okay then, so from all the various discussions I get the impression that the 
> consensus is
> 1) The easiest way to get the buffer into/out of PLplot would be to add a 
> command line option (e.g. -mfo filename and mfi filename) and have plplot 
> core code pick this up and write to/from it. this requires no propagation to 
> additional languages and ensures the
> 2) The file will consist of a header that will include a plplot identifier, a 
> file format version number, a flag for endianness, the size of the type used 
> for the coordinates (with the assumption that if this is ever increased to 32 
> bit then it will become a real rather than an int) and the type of float used 
> (e.g. 32 bit ieee). The file will then simply consist of a dump of the buffer.
> 3) In the future the buffer should be updated (probably internally and for 
> the file) so that each command is prepended with the size of the command. 
> This will allow new commands to be added or bugs to be fixed and still allow 
> reading of the buffer by older software versions.
> 4) In the future the buffer could be written to a memory mapped file, perhaps 
> by some known prefix to the file name or something. This will significantly 
> increase speed for real time communication between processes reading/writing 
> the buffer.
> 5) For now it seems sufficient to simply support reading/writing in native 
> format, but in future we would introduce conversion from various file 
> endianness and float formats into native format during reading.
> 
> Does this sound sensible?
> 
> I did some more work on the wxWidgets driver over the weekend and am 
> basically at a point where until this mechanism is sorted I can't really do 
> much more, unless I write a wxWidget driver specific version of this 
> transport mechanism and then we generalise it to plplot core code later. The 
> alternative is that we forget this as a general idea and I just implement 
> something for wxWidgets myself.
> 
> Phil
> 
>> On 11 January 2015 at 19:41, Alan W. Irwin <ir...@beluga.phys.uvic.ca> wrote:
>> On 2015-01-11 09:27-0000 Phil Rosenberg wrote:
>> 
>>> Regarding the "special values" where small errors in floating points lead
>>> to jumps in integer representation - I think this is probably dealt with
>>> now by anti-aliasing in most modern drivers.
>> 
>> No, it is worse than that.  Generally, we have PLFLT input which is
>> transformed to internal physical coordinates which are then
>> transformed again (usually by simple scaling) by device drivers into
>> the actual physical coordinates (pixels or whatever) that driver
>> understands.  So for certain magical combinations of input (which our
>> standard examples used to hit a lot), the internal physical coordinates
>> which are currently represented as 16-bit integers can flip to a
>> different integer causing a section of the whole plot to shift visibly
>> relative to the rest depending on platform.  (Here we are defining
>> platform as the combination of computer language, optimization for
>> that language, OS, and hardware).
>> 
>> In other words, the devices are following the orders they are given
>> (with or without antialiasing applied) by the internal physical
>> coordinates, but for magic input values those orders get changed by
>> +/- 1 integer out of the limited total range of 16-bit integers
>> depending on platform. We have historically adjusted our standard
>> examples to avoid these magic situations so that we get more
>> consistent test results comparing one platform with another.  But that
>> is just a cover up, and I would far prefer our internal physical
>> coordinates simply had a lot more resolution so that in full
>> generality regardless of input values the PLplot results always look
>> the same (with small rounding errors consistent with 64-bit doubles
>> rather than much larger and visible rounding errors consistent with
>> 16-bit integers) from one platform to the next.
>> 
>> 
>> Alan
>> __________________________
>> Alan W. Irwin
>> 
>> Astronomical research affiliation with Department of Physics and Astronomy,
>> University of Victoria (astrowww.phys.uvic.ca).
>> 
>> Programming affiliations with the FreeEOS equation-of-state
>> implementation for stellar interiors (freeeos.sf.net); the Time
>> Ephemerides project (timeephem.sf.net); PLplot scientific plotting
>> software package (plplot.sf.net); the libLASi project
>> (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
>> and the Linux Brochure Project (lbproject.sf.net).
>> __________________________
>> 
>> Linux-powered Science
>> __________________________
> 
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