MaplePrimes Posts

MaplePrimes Posts are for sharing your experiences, techniques and opinions about Maple, MapleSim and related products, as well as general interests in math and computing.

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  • No, the title does not come from hornybitches.com, nor does it mean something related to sex.

    I have been wondering about the reception of an independent patch Library for Maple.

    I'll lay out a few ideas, and then maybe some criticism (or indifference) might follow.

    I'm a bullet-point sort of person:

    • sourceforge project with a few willing experts for vetting and gatekeeping of submissions.
    • Patch .mla Library archive, going into /toolbox/Patch/lib/ so as to get picked up automatically by libname.
    • Self-building, with...

    On his blog, Jaime Zawinski (of Netscape and XEmacs fame) relates a tale of finding limits in the (supposedly) unlimited big number representation on a TI Lisp machine in the early 1990s. It is an amusing story, and it makes me wonder if GnuMP is has a similar limit on a different scale.  Or in other words, is there a positive integer small enough to fit into memory  (assuming 64 bit address space) but that cannot actually be constructed in GnuMP due to limits in the implementation? Does someone here know enough about the GnuMP internals to give the answer?

    I have been thinking about creating a Maple benchmark, to show a performance ranking versus operating system and hardware.

    Is there any interest in such a thing?

    If the results were put in a mapleprimes blog post, then they might be editable, and so could be updated as more items were submitted (messaged or emailed, to me, say).

    After having Maple for a week I'm happy with it but still have to learn a lot about the kinds of problems it can solve.  Here is a problem I solved many years ago whose solution I have misplaced.  I'm wondering if Maple could help me recover my solution.

    Write an expression for ab (a and b real) using only the unit (1) and the operations of adding, subtracting, and taking the reciprocal.

    I'm also curious whether this is a well-known problem.  As I recall, I didn't find any references to it when I worked on it before.

     

    Special Relativity has been around for ~100 years, General Relativity for ~90 years.  I'm hoping that with the assistance of Maple and Mapleprimes I may be able to do some tensor calculus to better understand Einstein.  Perhaps the twin paradox is within my reach.  Perhaps even the orbit of Mercury.

    In the following worksheet, evalf[4997](... does what I expected and evalf[4998](... does not.

    View 4937_Page147.mw on MapleNet or Download 4937_Page147.mw
    View file details

    See (3) and (10) in the worksheet.

    Something I've been wondering about...

    i am solving a heat equations with maple but i didn't work out. if you guys can get it out plz give me code. thanx a million

    diff(u1(x,t),t)=diff(diff(u1(x,t),x),x))-a*(u1(x,t)-u2(x,t))+b*(u3(x,t)-u1(x,t))
    diff(u2(x,t),t)=diff(diff(u2(x,t),x),x))-c*(u2(x,t)-u3(x,t))+a*(u1(x,t)-u2(x,t))
    diff(u3(x,t),t)=diff(diff(u3(x,t),x),x))-b*(u3(x,t)-u1(x,t))+c*(u2(x,t)-u3(x,t))

    i need the expression of the u1(x,t),u2(x,t),u3(x,t) and the a,b,c are constants.

    Looking forward to hearing from you!!!

     

    I've just reformatted my computer and NEED to reinstall Maple 11 ASAP,
    assignments are due soon.
    I am having trouble installing it
    
    1st time Installing)
    
       Everything was alrite until my cd-drive went haywire and the installiation frooze
       i then ended the task (task manager), maple as far as i know created the folder 
      program files, a few files there but NO WORKING PROGRAM is there leading to my second attempt to reinstall
    
    2nd time installing)
    
    "Maple 11 already installed"
      confused i decided to explore maple 11 folder, attempt an uninstall
    

    Hello,

    Another interesting undocumented package in the Maple 11.02 Library.

    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:

    View 178_Sudoku3-20-03-08.mw on MapleNet or Download 178_Sudoku3-20-03-08.mw
    View file details

    I just received and installed Maple 11.  (Maplesoft wouldn't sell me the student version, but I learned they have an unadvertised Home User version which is reasonable.  You have to call on the phone to order it.)  So far it's working well, but I can't figure out how to get an exact (symbolic) solution to a quartic with integer coefficients.

    Of all the ways to decompose a numerical (floating point) matrix, my favorite is the singular value decomposition (SVD).  There are a lot of applications of the SVD (see my dissertation for one related to polynomial algebra) but my favorite ones are probably two applications related to image processing.

    The first one I want to talk about comes from the cover of James Demmel's book "Applied Numerical Linear Algebra": image compression.  This example gives a really cool intuitive understanding of the Rank of Matrix and is also nice excuse to play with Maple's ImageTools package.

    So, the first thing you need a test image. I used the classic image compression benchmark of a Mandrill.



    Read this in with:


    mandrill:=ImageTools:-Read("4.2.03.tiff");


    The result is a 512x512x3 array.  In order to do something with this, we need to make it into a matrix so, call


    manmat:=convert(ArrayTools:-Reshape(mandrill, 512*3, 512), Matrix);


    Now we can compute a singular value decomposition of the image:


    (U, S, V) := LinearAlgebra:-SingularValues(manmat, output = ['U', 'S', 'Vt']);

    Now we can zero-out small singular values and multiply things back together to create low-rank approximations of the matrix that are also compressed versions of the image.
    Rank 32 will give us 1/8 of the data (64 dimension 512 vectors: 32 rows of U, 32 columns of V, and the 32 corresponding singular values) but still a pretty good image:


    rank32approx:=MatrixMatrixMultiply(`.`(U, DiagonalMatrix(S[1..32], 3*512, 512)), V, outputoptions = [order = C_order]);


    This reshape it back to an image and display:


    Preview((Reshape(rank32approx, 512, 512, 3)));


    Taking things down to rank 8, is leaving only 1/32 of the data, but it is amazing how what is left resembles the original image:


    rank8approx:=MatrixMatrixMultiply(`.`(U, DiagonalMatrix(S[1..8], 3*512, 512)), V, outputoptions = [order = C_order]);
    Preview((Reshape(rank8approx, 512, 512, 3)));


    To look at more images in order of descending rank, take a look at my worksheet:
    Download 5480_SVD-face-colour-improved.mw
    View file details

    Next time: eigenfaces

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