Re: MISSING and UNDEFINED

[Ethan A M. <merritt@u.washington.edu>]

On Sunday 18 June 2006 12:28 pm, you wrote:
> My feeling is that good programming practice would be to always go 
> back to the calling routine with some indication of whether this is 
> a DF_MISSING, DF_UNDEFINED or DF_BAD point and let the calling 
> routine handle it.

MISSING and UNDEFINED are indeed returned to the caller, but so far
the callers treat them the same way (plot2d.cline 446, plot3d.c line 688).

> Here is how it is for the patch in 2D
> 
> plot '-'
> 1 10
> 2 20
> 3 ?
> 4 40
> 5 50
> e
> 
> will treat the third point as (2,3) whether "missing" is properly 
> set or not.

I consider that a bug. But it's been documented as behaving like that
since forever, so I suppose we may be stuck with it.  To me it makes
no sense to interpret the different lines of input as having different
formats. I.e. if you read 2 values, X and Y, from lines 1 and 2 then
it's crazy to suddenly switch modes and interpret line 3 as having
an implicit X value and Y in column 1.   But this is a digression.

> But how about for a single column?
> 
> gnuplot> plot '-'
> input data ('e' ends) > 10
> input data ('e' ends) > 20
> input data ('e' ends) > ?
>               ^
>          Bad data on line 3
> 
> Ooop, that happens when missing is not defined AND when it is defined.

It works properly here.  Are you sure you correctly set missing?

> I would say that it should be ignored in the case of missing being defined... 
> so there is a bug right there even with the patch in my mind.  

Um. I see no bug. It works exactly as you say it should.

> Should I put together a demo?

I'm less interested in a demo than in a re-written section for the
docs.  Once we have agreed on a statement of what is supposed to 
happen, then we can do any required bug fixing or demo-writing.

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742