Re: Missing/invalid data points

[<br...@ph...>]

Ethan Merritt wrote:

> The second case keeps the point, marking it as undefined.
> That is better, but it would be better yet if the information
> stored was
>    0.3 NaN 3.33 u
> If nothing else, that would allow the tabular output line
> to match the original input line.  Beyond that, the extra
> info may be of use in auto-scaling the axes, 

Hardly --- autoscaling should never react to points that aren't
actually on the plot.

But that's not the actual point.  The core issue is that there's
only *one* "undefined" flag per data point.  To use the non-NaN
data values safely, datafile.c would have to record which of them are 
usable, i.e. which caused the DF_UNDEFINED, and which didn't.  And it 
would have to continue reading / filling after a NaN or missing column.

That's a rewrite from scratch of datafile.c and a good portion of all 
the code using it you've just outlined.