Why have you asked about this in 3 separate postings??

@Ronan If your procedure creates a Matrix (or Array) and associates it with a DataTable then your procedure should return that very same Matrix (or something that points to the same data in memory) and not a copy of it.

Calling convert(mat,Array) or copy(mat) are just two kinds of copying. Both break the association link with the DataTable. and both prevent subsequent updates to either DataTable or Matrix to be mirrored by changes in the other.

If you really need to construct the DataTable while using a Matrix for the variable=mat option (for performance reasons, apparently) then I suggest that you either return that same Matrix or try to use ArrayTools:-Alias to construct an Array.

The command ArrayTools:-Alias allows you to construct a new rtable (shell) that points to the very same data position in memory as another rtable. In contrast, the Reshape command makes a wholly new rtable (only copying the data over, which you don't want).

So you can construct an Array that points at the same data in memory as does some Matrix. So you could have an Array with indexing from zero, while still having your DataTable be associated with a Matrix, and updates to all three would be mirrored. That's what I understand to be your goal: data entry via DataTable, and, subsequently, zero-based programmatic access of the data.

I'm away from a computer right now, but I'll try and confirm later.

I changed all the references in your Question from "Maple 16" to "Maple 2016", since that is the version in which your attachment was last saved and is likely what you meant.

Maple 2016 was released in the year 2016, whereas Maple 16 was four major releases earlier and released in the year 2012.

I am looking forward to the year 2019.

@vv I agree that an `angle` option on `textplot` would be useful.

But I think that it would need to be dynamically constrained to the aspect ratio of the currently displayed values on the axes.

If it were only a fixed angle in terms of the screen then I don't think that it would be useful for nearly as many plotting tasks.

ps. Someone else showed the OP a link to my old posting about STL import and plotting of 3D letters.

@vv The OP has Maple 7, and plotting images on surfaces is functionality that came many major versions later. 

@rallezet I suspect that what you want can either be done via iteration and rtable_scanblock or possibly ImageTools:-Convolution (plus a few scans or masks, etc).

But your example is too scanty in details to proceed properly without going down the wrong road. Please provide a larger example that contains not just the highest and lowest values but also the boundary values and also some in between. Also useful would be a description of what you want to see in the 1st, 2nd frame, etc, if not the explicit first few frame's Matrices.

@das1404 A help page that almost every Maple user should read is for the topic plot,options . (You should read the one in your Maple 7, of course, and not the modern one in that Online Help link.)

In this case, it is the option style that is most relevent.

The style patchnogrid (now aka polygon) is not related to Maple's patchlevel. You are correct, it does mean that the polygon is filled (shaded) and its outline is not shown differently.

@das1404 Does this work in your Maple 7?

restart;

with(plottools):

makeA:=proc()
  local opts;
  opts:=style=patchnogrid,color=gray;
  plots[display](
    plots[polygonplot]([[0,0],[1,0],[4,8],[3,8]],opts),
    plots[polygonplot]([[3,8],[4,8],[7,0],[6,0]],opts),
    plots[polygonplot]([[2,4],[5,4],[5,3],[2,3]],opts),
  scaling=constrained);
end proc:

P1:=makeA():

P1;

plottools[rotate](P1, 2*Pi/3);

@das1404 You can delete the "uses" line inside the proc, and change each polygon to plots[polygon] instead.

But do keep using procedures, to organize your jobs. Write a procedure to create the plot of the capital "D".

Like all your previous queries, I converted this from a Post to a Question.

Are you saying that you want the different branches of the piecewise to be visually distinct? If so, then how do you want them to differ visually? With different colors? Or different styles for the lines?

Do you also want the different contour values to be distinct from each other, say by some graded shading?

If you want the piecewise branches to have distinct colors, and also the contour values to have graded shading, then perhaps you could suggest what colors and gradients you'd like.

Use the green up-arrow in the editor here to upload your actual worksheet or document.

It's unclear exactly what commands you've executed, otherwise.

@assma You should be able to use the ExportMatrix command with that numeric Matrix.

@Preben Alsholm That is weird. It seems to have changed between Maple 12.02 and Maple 13.00. (Report submitted)

@Joe Riel Hi Joe. I didn't mean that it's tough in principal. I meant that it's awkward and tough for most users to do by hand.

After all, calling if...then with is in the conditional is clearly tough for many users to figure out, since it is a faq.

This thread strikes me as being in the classic theme of technical correctness versus practicality. A didactic view is to restrict attempts to only classes of problem for which results may be guaranteed, etc. But that approach would never have given us the awesome usefulness of the simplify command.