When Maple receives a request to interrupt its current computation, it does not just stop everything it's doing and quit.

As I understand it, Maple continues it computation until it reaches a "safe state" from which it can stop. This is done so as to allow the Maple process to continue on a new task with predictable values of all variables. This is more complicated than it might seem at first; just think about all of the procedures that are called - sometimes recursively - for some relatively simple requests. (Your choice of matrix determinant might be just one such example.)

That said, I have had many instances where it appears that Maple has not received my request to interrupt its current computation. What would make me happier is to have Maple respond immediately with an acknowledgement that the interrupt request has been received. Maybe there could even be a way for users to enter a second request that tells Maple to just quit without regard to its state.

These decision processes are really quite natural. They happen almost every day in my life. When it's time to go home I try to get to a convenient stopping point. But, if I have to pick up one of the children, then I have to just stop what I am doing and hope that I can pick it back without out losing too much of what I was doing at that time.

If I'm off target, I hope someone will set me straight.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

deplot and deplot3d are different from odeplot

odeplot is in the plots package (?odeplot)

deplot and deplot3d are in the DEtools package (?DEtools, ?DEplot and ?DEplot3d)

There are a lot of similarities between the commands, but also some important differences. As in your example, odeplot is a little more flexible when it comes to specifying exactly what you want to plot. I am more likely to use the DEplot command when I want to perform visualize the direction field (to learn, say, how solutions might behave for wide ranges of initial conditions).

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

I can combine your last five commands into a single line that is quite understandable.

The key is to be aware of the odeplot command (in the plots package). This command is designed specifically to plot the numerical solution of an initial value problem. Here is my version of your code:

restart;
m:=t->M*exp(-gamma*t)+M[0]:
rocket_eq:=m(t)*diff(x(t),t,t)+diff(m(t),t)*u+m(t)*g=0:
params := [M[0]=0.2, M=1, gamma=10, u=8, g=9.81]:
rocket_eq:=eval(rocket_eq,params):
ics:=x(0)=0,D(x)(0)=0:
sol:=dsolve({rocket_eq,ics},x(t),numeric):
plots:-odeplot(sol, [[t,x(t)],[t,diff(x(t),t)]], t=0..2, color=[black,red],legend=["position","velocity"]);

The odeplot command can do much more than this; see ?plots,odeplot for full details.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Could you please post your full worksheet? That would be the best way for someone to see exactly what you are doing and to suggest a way to improve performance.

For starters, I wonder if Maple could not do some of the integration symbolically. This would delay the need for numerics and could be a big time saver, not to mention better numerical results. And, if numerical integration is going to be use, why spend the time with IntegrationTools:-Expand?

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Could you please post your full worksheet? That would be the best way for someone to see exactly what you are doing and to suggest a way to improve performance.

For starters, I wonder if Maple could not do some of the integration symbolically. This would delay the need for numerics and could be a big time saver, not to mention better numerical results. And, if numerical integration is going to be use, why spend the time with IntegrationTools:-Expand?

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

This does work, but pagan's suggestion is going to be more efficient (if that becomes an issue).

One improvement I would suggest to your implementation is that there is no need to reverse the entries in the permutations. You can replace your line

aaa[op(4,ind),op(3,ind),op(2,ind),op(1,ind)]:=aaa[i,j,k,m];

with

aaa[ind[]]:=aaa[i,j,k,m];

Glad I could be of some help.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

This does work, but pagan's suggestion is going to be more efficient (if that becomes an issue).

One improvement I would suggest to your implementation is that there is no need to reverse the entries in the permutations. You can replace your line

aaa[op(4,ind),op(3,ind),op(2,ind),op(1,ind)]:=aaa[i,j,k,m];

with

aaa[ind[]]:=aaa[i,j,k,m];

Glad I could be of some help.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

While this is possible, a real question is how many users will not like the new default? Personally, I don't want Maple to make too many assumptions about what I'm intending for it to do. That's my job, in the instructions that I ask it to execute for me.

My opinions do not change when I think about using Maple in educational settings. Software that makes assumptions about what the students are trying to do only contributes to continued student laziness and lack of attention to detail.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

While this is possible, a real question is how many users will not like the new default? Personally, I don't want Maple to make too many assumptions about what I'm intending for it to do. That's my job, in the instructions that I ask it to execute for me.

My opinions do not change when I think about using Maple in educational settings. Software that makes assumptions about what the students are trying to do only contributes to continued student laziness and lack of attention to detail.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Thank you.

Looking at this, I now see that I also need to update the document for Maple 13. Great - more work!

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Will,

Makes sense. I apologize for not recognizing this (obvious) distinction earlier.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Will,

Sure. Here is a screenshot showing what I see in both IE (left) and Firefox (right).

In each of these I have expanded the Administration section (at the top) and the Inport format (at the bottom - but not visible in this screenshot).

I had a hard time reading the details in your screenshot. Maybe these would come through better via e-mail?

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Bryon,

I do not see what you describe.

I do not see a field labeled "MaplePrimes Forums" or a drop down box with a list of forums.

I don not see any submit/delete buttons or a subheader labeled "publishing options".

I'm guessing there is some setting that needs to be updated so that I (and others?) can see the fields you described.

Doug

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

While the instructions all sound great, I have two questions about how to use what is in these instructions. To be specific, let's focus on these two paragraphs:

Redirect posts to a more appropriate forum
If a message is posted that obviously belongs somewhere else, you can assign it to a new category by using the edit function for that message.

Promoting messages or blog posts to the front page
If there is a particularly good blog post, or a message posted that you think warrants promotion to the front page of MaplePrimes, you can do so.  In the edit screen, open up the “publishing options” menu and click “Promoted to front page”.

How can I assign a message to a new category using the edit function of the message?

When click on an edit hyperlink I see the message with a closed Administration section and a closed Input Format section. The Input Format concerns the formatting of the message: HTML, Filtered or Full, or Text or ... . The Administration section shows the date the message was posted, the author of the message, and whether the message is published or not. I do not see anything about moving a message to a new category.

Likewise, I do not see a Publishing Options menu or any other sign of a Promote to Front Page feature.

Am I missing something? Do other moderators see anything different?

Thanks in advance,

Doug

P.S. When I edit this message the two quoted paragraphs are indented. But, when i click on Post Comment they appear flush along the left column. (I am using Firefox, if that matters.)

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

It's a nice coincidence that I re-read David Clayworth's blog entry on Making Plots Zoom only one day after posting about the user's role in creating a decent plot of the tangent function. In my opinion, before "smartplots" are truly useful, they need (at least) 2 improvements:

1. to be able to support the type of refinements described in my previous post
2. to have the ability to export the final settings.

I'll use the tangent function to elaborate. Suppose I start with

smartplot( tan(x) );

I can follow DJ's suggestion to use the mouse to change the viewing window. But, this changes both dimensions. How do I change only the vertical (or only the horizontal) range? The only way I known to do this is via the context menu (Axes -> Properties ...). I don't see any way to use the interface to specify discont=true.

When I do change the viewing window via the Axis Properties popup, I can't use Maple constants like Pi - all ranges must be explicitly numeric. (The resampling is obvious if you make the viewing window larger than the current window.)

Once I do get a plot looking the way I like it, I'd like a way to reproduce this plot without going through the entire customization again.

The PlotBuilder (see ?worksheet,interactive,plot ) does give you more control over the plot, including support for, e.g., Pi in the ranges and for identifying discontinuities. You can monitor your progress through the Preview button. I particularly like the fact that you can get the command corresponding to your specific plot (click the Command button). Also, if you call PlotBuilder again on the same expression, it sometimes remembers your most recent settings - making it easier to go back and refine your options.

I would like to see more of the PlotBuilder's functionality incorporated into the clickable interface for smartplots.

Doug

P.S. I am going to link this to the Maple 15 - Wish List discussion.

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Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu