# Items tagged with commentcomment Tagged Items Feed

### Embedded components, maplets, and sudoku...

March 20 2008 by Maple

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My oldest son, Stuart, recently completed a Science Fair project on sudoku puzzles. While I am fairly good at solving sudoku puzzles, the mathematics is something that is completely outside my area of expertise. After seeing the paper by Hurzberg and Murty in the Notices of the AMS (June/July 2007) and additional papers by Felgenhauer and Jarvis (http://www.afjarvis.staff.shef.ac.uk/maths/felgenhauer_jarvis_spec1.pdf)  and Russell and Jarvis (http://www.afjarvis.staff.shef.ac.uk/maths/russell_jarvis_spec2.pdf) and Jarvis' sudoku webpage (http://www.afjarvis.staff.shef.ac.uk/sudoku/), I felt that I had a reasonable understanding of some of the basic ideas involved in counting unique sudoku puzzles. While I had nothing to add to the mathematical ideas, I did see the potential to create a tool to visualize these ideas. The result is the worksheet I just uploaded to MaplePrimes:

### homalg

March 15 2008 by

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Does anyone here use this?

Would it be useful for someone new to topology/homological algebra learning wise ?

thanks,

dc

http://wwwb.math.rwth-aachen.de/homalg/

March 14 2008 by

The e-mail notification feature that was previously available before the last update to the site has been re-enabled.

March 14 2008 by

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I used to receive emails each time when a comment/reply was made to my questions on mapleprimes. Very convenient. Now this service either stopped to exist or something else, as I receive nothing. Can it be resumed somehow? Thanks.

### efficient sums evaluation?

March 14 2008 by Maple

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probably I should not have written my question as a comment here
http://www.mapleprimes.com/forum/how-to-evaluate-faster, si I now put it as a new topic. Thanks for your time and help.

The problem is to evaluate as effectively as possible an n-fold sum of N additions, e.g., for n=3

FF := proc (N) options operator, arrow; evalhf(add(add(add((1/2*1/3*1/4)*(1/2)^j*(3/4)^g*(2/3)^i/(.4*i+.4+.1*j+.1+.3*g+.3), i = 0 .. N), j = 0 .. N), g = 0 .. N)) end proc

### I need some information about if

February 27 2008 by Maple

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Hi, I can't find any information what does FI mean, for example: f := proc(x) if x>0 then x else -x fi; end proc: f(-3); or: if iseuler(G) then continue else RETURN (print ("The graph does not have an Euler circuit")) fi; I'm tired of googling already, Maple Help doesn't have any information about fi, what might it be? perhaps some closing declaration instead of 'end if'? I would be grateful for any comments, thanks in advance, Sven

### Recursive Types

February 22 2008 by Maple

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John Fredsted suggested using the following procedure (slightly modified) to determine whether an expression was deeply algebraic.

isDeeplyAlgebraic := proc(x)
if not type(x,'algebraic') then false
elif type(x,'atomic') then true
else andmap(procname,x)
end if
end proc:
Rather than using a procedure as a predicate, this seems more usefully expressed as a type.  A nice way to  do that is with Maple's TypeTools[AddType] procedure.  For example
TypeTools:-AddType('DeeplyAlgebraic1'
, proc(x)
if not x :: 'algebraic' then false;
elif x :: 'atomic' then true;
else andmap(type,x,'DeeplyAlgebraic1');
end if;
end proc);


### Cubic Rubik Maplet

February 21 2008 by

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My humble work - CubicRubik Maplet. Interactive Game of ordering CubicRubik.

### Why andmap and ormap ?

February 19 2008 by

In working out the procedure isDeeplyAlgebraic in the post Deeply algebraic, I was trying to use something like and and or, analogously to +, *, ., etc.

### Externally stored images

February 18 2008 by

In the thread An easy way to plot the region between two curves there are several pictures which are externally stored, i.e., they have not been uploaded to mapleprimes, but instead the sources of the images point to some outside site.

That should work, I think, but it does not, at least not where I am sitting. I see some Chinese looking art with http://blog.163.com/ (the external site at which they are stored, I assume) at the bottom of each picture.

### Vector Question

February 17 2008 by Maple

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I need to answer a question, using maple, mathcad, or a similar algebra solver.

I have a little experience in Maple, and thought it would be easy, buts its not, here is the question.

The question is

-----

Let P and Q be two points in the x-y plane with coordinates (1,2)  and (1,-1) respectively with respect to an origin O. Express OP, OQ and QP in the form Ai  + Bj   where A and B are scalars. Let R be a point on OP so that OR = 1/3OP . Find OR and QR in terms of i  and j .

-----

I have no idea how to do this.

### Geometry In Maple

February 17 2008 by Maple

0

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I need to answer a question, using maple, mathcad, or a similar algebra solver.

I have a little experience in Maple, and thought it would be easy, buts its not, here is the question.

The question is

-----

Let P and Q be two points in the x-y plane with coordinates (1,2)  and (1,-1) respectively with respect to an origin O. Express OP, OQ and QP in the form Ai  + Bj   where A and B are scalars. Let R be a point on OP so that OR = 1/3OP . Find OR and QR in terms of i  and j .

-----

I have no idea how to do this.

February 16 2008 by

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Currently, with "Comment viewing options" set to 50 (the default), I see 6 comments in the 2nd page, but clicking on their links on the block "Recent Coments" send the browser (Firefox) to the top of the first page.

Could you solve this problem?

### Plotting procedure solutions

February 13 2008 by Maple

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A procedure named curve(x) in the attached worksheet solves several equations, each dependent on the solution to the previous equation.  The problem is that when I issue the plot command for a range of the dependent variable x, the equation result that gets plotted is not for the result of the solution to the last equation for P.  Specifically, I would like to issue the "plot(curve,0.0..0.5, <other format commands>);" and get a plot of k vs. P.  Currently the plot is of k vs. P_bar.  Your comments are appreciated.

### Move to Suggestions?

February 06 2008 by

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Comments have been closed on this post since it has become difficult to follow the many threads of discusson. Please post to the MaplePrimes suggestions forum with any comments that you have on the new site

Should we repost on this forum the comments made on your blog "Welcome to the Updated MaplePrimes" ?

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