Multiple commands in Evaluate expressions

[Andreas Winter]

In the evaluate expressions dialog it is now possible to enter more than one command at once. (Grace has been able to accept this, but in QtGrace this was not working correctely). To enter more than one command either separate the commands via ';' or via new lines.

QtGrace v0.2.6

[sanfo]

I don't know if this is connected to the recent changes, but I encounter the following problem: if I select as destination and already-existing set, if I type a wrong formula (i.e. a formula that cannot be parsed correctly), at the same time when the error is raised, the destination set is erased, and this cannot be undone - the destination set is lost forever!

[Andreas Winter]

Dear Francesco;

I could not reproduce this.
Can you please give me an exact example (like: what you entered in the dialog before pressing Apply)? Thank you!

Best regards
andwin

[sanfo]

In fact I cannot reproduce it either at the moment, though it happened already to me several times (always in conjunction with a wrong formula).

I will report with more details as I encounter it again

[sanfo]

Hi Andwin, I came out with the problem again and I have a neat reproducible case

$ cat /tmp/ciccio
1 1
0 2
2 2
$ qtgrace /tmp/ciccio

now try:

Data->Transformations->Interpolation/splines...

Select S0 set on both source and destination

Start at 0
Ends at 2
Length 2
(all of this is irrelevant but let's keep it concrete)

You will get the erorr:

$ qtCan't interpolate a set with non-monotonic abscissas
Error in do_interp()

and the set has disappeared, without this operations being undoable.
I think this is related to some deep glitch, as I had noticed it happening in "Evaluate" dialog as well (see my OP)

[Andreas Winter]

Dear Francesco;

I don't think this is related.
Qtgrace was unable to interpolate the same set for source and destination. I think xmgrace had the same problem. The interpolation algorithm worked locally, i.e. it looked in the sources for the interpolation of one value. If source=destination the source is overwritten and the interpolation stops after the first point. I think I already removed this bug, but I have not uploaded the sources yet.

I still can not reproduce your bug from your OP.

Best regards
andwin

[sanfo]

The point that I wanted to address is that in this situation the Undo does not work properly, in the sense that the set is lost and you cannot recover it.

So there are 2 different problems:
a) the set is lost - why? shouldn't an empty set be created in place?
b) the undo does not work - should it? Isn't the state before the operation saved in the stack?

but I don't understand if and how they are related to each other

On a separate path, I think that at the cost of making a temporary copy one could easily have the possibility to overwrite the source. This would automatically solve the previous problems.

[Andreas Winter]

Dear Francesco;

The problem is, that QtGrace does not recognize, that something has been modified and therefore does not create an undo-node.
The problem with source=destination for interpolation has been resolved (even before you commented about it).
I still can not reproduce your bug from your OP.
Please let me know about your thought about this whole thread here. I can not see any issues that I could work on at the moment until we find a way to reproduce the bug from your OP.

Best regards
andwin