Doug Meade

 

Doug

---------------------------------------------------------------------
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

MaplePrimes Activity


These are replies submitted by Doug Meade

Alec,

I talked with a few people (e.g., Dave Hare) who work on the "mathematics" side of the product, and I know Paulina. I do not recall having too many deep "mathematical" discussions during this visit. Most of my disucssions were related to the GUI.

If you are asking if I learned of any earthshattering new mathematical capabilities that we should expect to see soon, I'm afraid I can't fulfill this request. (I would encourage you to see my Maple 15 Wish List blog entry.

My requests tend to be rather basic: I'd like Maple to do a better job of recognizing, and dealing with, removable singularities and I'd like Maple to be able to treat sequential limits in a serious way. For the latter, I mean that I'd like a way to Maple evaluate limit( sin(n*Pi), n=infinity ); to 0 (maybe with some additional argument to tell Maple that n in an integer).

If you have a specific question in mind, please ask.

Doug

---------------------------------------------------------------------
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

My suggestions were tested only from a worksheet.

I see the same behavior as  you report when in document mode. I believe the explanation for this is that the structure of a "document" is very different from a "worksheet". In a document you don't have any "input regions" unless you explicitly create one. When you do, then the setting of Maple Notation comes into play. Otherwise, you are creating a document and so your keystrokes are treated differently.

Personally, I tend to use Maple to perform calculations and create plots that I transfer to other settings: webpage, PowerPoint, LaTeX, .... Only when I want to use Maple to create the final presentation do I use it in "document" mode. The rest of the time I use "worksheets".

Doug

---------------------------------------------------------------------
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

My suggestions were tested only from a worksheet.

I see the same behavior as  you report when in document mode. I believe the explanation for this is that the structure of a "document" is very different from a "worksheet". In a document you don't have any "input regions" unless you explicitly create one. When you do, then the setting of Maple Notation comes into play. Otherwise, you are creating a document and so your keystrokes are treated differently.

Personally, I tend to use Maple to perform calculations and create plots that I transfer to other settings: webpage, PowerPoint, LaTeX, .... Only when I want to use Maple to create the final presentation do I use it in "document" mode. The rest of the time I use "worksheets".

Doug

---------------------------------------------------------------------
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

Robert,

Makes sense, in an unfortunate way. Thank you for the explanation. I, too, hope this is resolved before the new MaplePrimes is released.

Doug

---------------------------------------------------------------------
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

George,

I have no doubt this works for you. I've uploaded many images to MaplePrimes, but for the last few weeks, it does not show the image I've selected. Rather, it shows one that was selected previously. My question is where is the source for this problem?

Let's see if I can demonstrate. Here's some code to create a direction field for an ODE:

with(DEtools):
 DEplot(diff(y(x),x)=sin(y(x)), y(x), x=-3..3, y=-5..5);


This is a JPEG file; this is not a problem. But, now if I add an initial condition - and save this plot as a GIF file - when I upload the GIF file, the previous JPEG appears.

DEplot(diff(y(x),x)=sin(y(x)), y(x), x=-3..3, y=-5..5, [[y(Pi)=2],[y(Pi)=-2]] );


This was supposed to be the JPEG with 2 solution curves, but it shows the image I saved with only one solution curve.

If I upload the GIF version of this image, what I actually get is the JPEG version:

This should have been the GIF version of the plot with 2 solution curves, but it's the JPEG image with one solution curve - the last successfully uploaded image.

I do see that the GIF and JPEG versions of the plots with 1 and 2 solution curves have been uploaded, and appear in the list of recently uploaded files. But, still the wrong image is in my posts.

Doug

---------------------------------------------------------------------
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

 

Or, with your original definition of p (as a procedure),

muller(p(x),-13,-12,-11,.000001,100,r1);

Doug

---------------------------------------------------------------------
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

Or, with your original definition of p (as a procedure),

muller(p(x),-13,-12,-11,.000001,100,r1);

Doug

---------------------------------------------------------------------
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

Roman's response answers your specific question, but I want to be sure you are aware the approach with the display function is still an option. The example below shows that display knows how to combine plots with different domains. It is not a problem if, as in your example, the domains are disjoint.

P1 := plot( x^2, x=-2..2 ):
P2 := plot( [sqrt(x),-sqrt(x)], x=0..4, color=[blue,green] ):
plots:-display( [P1,P2] );
 

I have the plot to include in this example, but the upload button is not working properly - it keeps showing me the last file I uploaded, not the current one I am trying to upload.

Doug

---------------------------------------------------------------------
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

The point is visible in Maple 13.

But, I can see why you think it's not been plotted. To better illustrate, let's change the symbol and symbolsize to make it easier to see the points:

with(plots):
pointplot3d({[2,3,4],[1,2,3],[4,5,6]},symbol=solidsphere,axes=boxed,
            symbolsize=20);

There are a couple of problems with Maple's plot.

First, the tickmarks for the y axis appear to be 2, 3, 4, 4 - the second 4 is the last tickmark for the x-axis. (This is why you thought Maple cut off the axes - it had me fooled for a few minutes, too.)

Next, the first and third points both appear in corners of the "box" produced by axes=boxed. The first is visible, but the third appears only as a shadow

If I change symbol, symbolsize, and color, it's much easier to see that all three points are plotted.

pointplot3d({[2,3,4],[1,2,3],[4,5,6]},symbol=solidsphere,axes=boxed,
            symbolsize=20, color=red);

So, Maple did plot your points, but it did not do so in any way that is not very satisfying. I hope this can be addressed quickly.

Doug

---------------------------------------------------------------------
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

Hows this?

with( LinearAlgebra ):
for j to ColumnDimension(B) do
  convert( subsop( j=NULL, convert(B[1..-1,j], list) ), `+` )
end do;

I'm there will be other suggestions. This version has the advantage that it's fairly readable.

Doug

---------------------------------------------------------------------
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

Hows this?

with( LinearAlgebra ):
for j to ColumnDimension(B) do
  convert( subsop( j=NULL, convert(B[1..-1,j], list) ), `+` )
end do;

I'm there will be other suggestions. This version has the advantage that it's fairly readable.

Doug

---------------------------------------------------------------------
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

If you need an outer loop for the columns (j), use one:

for j from 1 to 3 do
  (* whatever you want to do to column j *)
end do;

Also, I wonder if might not be easier to compute your sum of all non-diagonal elements of a column by finding the full column sum and then subtracting the diagonal entry. Like this:

B := LinearAlgebra:-RandomMatrix( 3, 3 );
                                 [ 57  -76  -32]
                                 [             ]
                            B := [ 27  -72  -74]
                                 [             ]
                                 [-93   -2   -4]
for j from 1 to 3 do
  add( B[i,j], i=1..3 ) - B[j,j];
end do;
                                     -66
                                     -78
                                    -106

Hoping at least one of these ideas is of some use,

Doug

---------------------------------------------------------------------
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

If you need an outer loop for the columns (j), use one:

for j from 1 to 3 do
  (* whatever you want to do to column j *)
end do;

Also, I wonder if might not be easier to compute your sum of all non-diagonal elements of a column by finding the full column sum and then subtracting the diagonal entry. Like this:

B := LinearAlgebra:-RandomMatrix( 3, 3 );
                                 [ 57  -76  -32]
                                 [             ]
                            B := [ 27  -72  -74]
                                 [             ]
                                 [-93   -2   -4]
for j from 1 to 3 do
  add( B[i,j], i=1..3 ) - B[j,j];
end do;
                                     -66
                                     -78
                                    -106

Hoping at least one of these ideas is of some use,

Doug

---------------------------------------------------------------------
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

The preference of cos over sin is a choice the Maple developers made (a long time ago). There are ways you can override this, but then you get into the situation where all occurrences of cos(t)^2 will be converted to 1-sin(t)^2.

This is something most experienced Maple users just accept.

Doug

---------------------------------------------------------------------
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

The preference of cos over sin is a choice the Maple developers made (a long time ago). There are ways you can override this, but then you get into the situation where all occurrences of cos(t)^2 will be converted to 1-sin(t)^2.

This is something most experienced Maple users just accept.

Doug

---------------------------------------------------------------------
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
First 8 9 10 11 12 13 14 Last Page 10 of 76