[Gnuplot-info] Gnuplot is interpolating missing data

[Dave H. <da...@ho...>]

Gnuplot 5.4.3 on old MacBook Pro running High Sierra.

I have many graphs which have missing data e.g. I was too lazy to record 
it on that day etc; these are indicated with "x" in the data file.

Now, hie thee to http://www.horsfall.org/bike.pdf which is a graph of the 
progress (if any) that I am making on my exercise bike; the "brake" is the 
friction adjustment and does not seem to be in any particular unit.

For laughs I compute an overall "effort" value which is the product of the 
distance and the brake (I was forced to rescale it by taking the square 
root to both make it fit and to make it look better, but that's irrelevant 
here).

Notice how the recorded data is interpolated over the missing data, yet 
the computed plot shows a gap (the desired behaviour).

(I do not use `set datafile missing "x"' anywhere)

Oddly enough my other graphs such as www.horsfall.org/health.pdf etc are 
fine; the only difference is the linetype where I am using "lt rgb" and no 
"pt", whereas with my exercise bike I am using a specific point type to be 
compatible with both a colour inkjet and a mono laser.

Is this expected behaviour?  It looks like a bug to me...

Attached are the relevant *.dat and *.gp files.

Thanks.

 -- Dave