Operate on X with _coarse_ time format data ?

[bfennema]

The following is a query because I do not claim that this should work, given that the time stamp is too coarse.

I have a file with data that is sampled faster than a second but the time tag is like

19/10/2011 15:54:50 10
(repeat 8 ) 11,13 etc
19/10/2011 15:54:50 21
19/10/2011 15:54:51 21
(repeat 8)
19/10/2011 15:54:51

So in other words my time stamp is too coarse for the data (it should have been 50.1,50.2 etc)

Regular X,Y plots all look perfect and display the time in the x-axis
which is a bonus.

In order to subtract Y=Y(n+1) - Y(n) I run Operate on X and add X+1 on a copy of the curve.

This modifies the time stamp to:

31/12/1899 0:00:00

and collapses all my data into a single point (with X=0) -

I am not sure whether this is because I execute +1 on a time stamp or
because there are gaps in my time.

When I load the data via colum=0 for X (which gives the increment) everything works fine, but I lose the nice time label in the graphs.

By the way, I really like this Plotting tool - you can make eally nice graphs quickly - my days of struggling with Excel are over !!

B.

[DPlotAdmin]

From my phone, so this may not be entirely correct but should be close. Use Operate on X with X=(15+54/60+(50+$N*0.1)/3600)/24. The $N will be replaced with the point index.

[DPlotAdmin]

Aaarrgghh. Nevermind. $N is apparently only in my head and not supported.

[DPlotAdmin]

Sorry for the runaround earlier. There's a decent reason that my imagined $N is not included in the text placeholders: in most of the functions that accept an equation, the placeholder represents a constant (minimum Y, for example) for all points within a curve. The point index obviously isn't constant for all points. But I have gone ahead and added j or J as the point index, useful only with Operate on X and Operate on Y. That will be available in the next release.

In the meantime you can still do what you want, though it isn't exactly straightforward. On your graph, create a new curve with Generate>Y=f(X) and Y=
(15+54/60+(49.9+X*0.1)/3600)/24
with X from 1 through however many points you have and incremented by 1. Now select Generate>Switch Independent Variable and in the curve list select the curve you just created.

[bfennema]

Excellent - that is perfect.

I really like it that you have exposed internals such as X Y, indepedent variables etc.

It gives you a great flexibility to process the data sets - also it is fast.

A great product - I am sold !

B.