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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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  • Yesterday afternoon, we updated MaplePrimes. The purpose of the update was primarily to squash some bugs and improve user experience.

    Highlights of the update include:

    • The ordering of replies has been corrected, as described in this post by Carl Love.

    • We fixed a problem whereby some members were unable to attach a file to a question or post.

    • Flagging a comment now works correctly.

    • Broken images that were appearing on some of our older posts have been restored. In addition, some older posts had incorrect dates, and these have been restored.

    • Some embedded links to user profiles or messages were resulting in errors, and have been corrected.

    • After receiving a badge, members will now be notified via a pop-up message.


    A number of other small improvements were made as well.

    As always, thank you for letting us know when you encounter a problem, and please continue to do so. We take note of everything that you report, and we try our best to prioritize and take care of the issues.

    Bryon

    Voting is now open for the next individual prize to be awarded as part of the Möbius App Challenge.  The winner will receive an Xbox One Prize Pack! 

    Here are the finalist Apps:

    Note that, if you ever have any problems viewing Apps in your browser, or simply want to work offline, you can always download a Möbius App and view it in Maple or the free Maple Player. To download a Möbius App, follow the link to the App and then click on the Download button near the top left of the page.

    You can vote for your favorite through our Facebook page or, if you’re not on Facebook, send an email with your vote to Mobius-Project@maplesoft.com.

    And remember, we are now accepting entries for the next quarterly prize. You could win a Music Prize Pack, including the 64GB 5th Generation Apple iPod Touch, Sennheiser In-Ear Noise Cancelling Headphones and the Bose SoundLink Bluetooth Speaker III!  See the Möbuis App Challenge for details.

    Voting closes April 25th, 2014.

     

    This is a little more than a new game it potentially uncovers a new class of numbers -- though determining membership might become a hard problem.

    A number that possesses the solitaire property can be written in as ...,0,...1,...2,...etc, or ...,0,...1,...10...11,...etc,(where the "0" is the first zero in the number), with a radix point anywhere. We are free to pick the base and say it is solitaire with respect to that base. After the initial 0, the subsequent ordinals (the 1,2, etc or the 1,10,11, etc) used to write the solitaire number don't have to be the first ones. For example:

    pi=3.1415926535897932384626433832795
    0 2884
    1 971693993751058
    2 0974944592
    3 078163860
    4 ...
    etc.,

    or

    pi=3.1415926535897932384626433832795

    0 2884197

    1 6939937510582 097494459

    2 3 07816

    3 860
    4 ...
    etc.,are both acceptable. (If the number can be written as  ...,0,...1,...2,...etc, or ...,0,...1,...10...11,...etc. it is solitaire.)

    The Champernowne constant with respect to base 10 has only one representation:

    0.

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    11...

    etc. .

     

    I know Base 10 Champernowne constant is base 10 solitaire. I can not say the same with certainty for Pi.

    I also propose we can measure the solitude of a number by the average amount of numbers between the 0,1,2,3..., and give a perfect solitude score to Base 10 Champernowne constant. Other constants can be given additional credit, of some kind, if the amounts of numbers between the 1,2,3... follow a specific preset pattern.

     

     

    marvinrayburns.com

     

    With the package VectorCalculus we can study the speed and acceleration to their respective components. Considering the visualizaccion and algebraic calculations and to check with their respective commands. Both 2D and 3D.

     

    Velocidad-Aceleració.mw     (in spanish)

     

    Lenin Araujo Castillo

    Physics Pure

    Computer Science

    The attached presentation is the last one of a sequence of three on Quantum Mechanics using Computer Algebra, covering the field equation for a quantum system of identical particles, its stationary solutions and the equations for small perturbations around them and, in this third presentation, the conditions for superfluidity of such a system of identical particles at low temperature. The novelty is again in how to tackle these problems in a computer algebra worksheet.

    The Landau criterion for Superfluidity
      

    Pascal Szriftgiser1 and Edgardo S. Cheb-Terrab2 

    (1) Laboratoire PhLAM, UMR CNRS 8523, Université Lille 1, F-59655, France

    (2) Maplesoft, Canada

     

    A Bose-Einstein Condensate (BEC) is a medium constituted by identical bosonic particles at very low temperature that all share the same quantum wave function. Let's consider an impurity of mass M, moving inside a BEC, its interaction with the condensate being weak. At some point the impurity might create an excitation of energy `&hbar;`*omega[k] and momentum `&hbar;` `#mover(mi("k"),mo("&rarr;"))`. We assume that this excitation is well described by Bogoliubov's equations for small perturbations `&delta;&varphi;` around the stationary solutions `&varphi;```of the field equations for the system. In that case, the Landau criterion for superfluidity states that if the impurity velocityLinearAlgebra[Norm](`#mover(mi("v"),mo("&rarr;"))`) is lower than a critical velocity v[c] (equal to the BEC sound velocity), no excitation can be created (or destroyed) by the impurity. Otherwise, it would violate conservation of energy and momentum. So that, if LinearAlgebra[Norm](`#mover(mi("v"),mo("&rarr;"))`) < v[c] the impurity will move within the condensate without dissipation or momentum exchange, the condensate is superfluid (Phys. Rev. Lett. 85, 483 (2000)). Note: low temperature liquid 4He is a well known example of superfluid that can, for instance, flow through narrow capillaries with no dissipation. However, for superfluid helium, the critical velocity is lower than the sound velocity. This is explained by the fact that liquid 4He is a strongly interacting medium. We are here rather considering the case of weakly interacting cold atomic gases.

    Landau criterion for superfluidity

     

     

    Background: For a BEC close to its ground state (at temperature T = 0 K), its excitations are well described by small perturbations around the stationary state of the BEC. The energy of an excitation is then given by the Bogoliubov dispersion relation (derived previously in Mapleprimes "Quantum Mechanics using computer algebra II").

     

    epsilon[k] = `&hbar;`*omega[k] and `&hbar;`*omega[k] = `&+-`(sqrt(k^4*`&hbar;`^4/(4*m^2)+k^2*`&hbar;`^2*G*n/m))

     

    where G is the atom-atom interaction constant, n is the density of particles, m is the mass of the condensed particles, k is the wave-vector of the excitations and omega[k] their pulsation (2*Pi time the frequency). Typically, there are two possible types of excitations, depending on the wave-vector k:

    • 

    In the limit: proc (k) options operator, arrow; 0 end proc, "epsilon[k]&sim;`&hbar;`*k*"v[c] with v[c] = sqrt(G*n/m), this relation is linear in k and is typical of a massless quasi-particle, i.e. a phonon excitation.

    • 

    In the limit: proc (k) options operator, arrow; infinity end proc, `&sim;`(epsilon[k], `&hbar;`^2*k^2/(2*m)) which is the dispersion relation of a free particle of mass "m,"i.e. one single atom of the BEC.

     

    Problem: An impurity of mass M moves with velocity `#mover(mi("v"),mo("&rarr;"))` within such a condensate and creates an excitation with wave-vector `#mover(mi("k"),mo("&rarr;"))`. After the interaction process, the impurity is scattered with velocity `#mover(mi("w"),mo("&rarr;"))`.

     

    a) Departing from Bogoliubov's dispersion relation, plus energy and momentum conservation, show that, in order to create an excitation, the impurity must move with an initial velocity

     

    LinearAlgebra[Norm](`#mover(mi("v"),mo("&rarr;"))`) >= v[c] and v[c] = sqrt(G*n/m)

     

      

    When LinearAlgebra[Norm](`#mover(mi("v"),mo("&rarr;"))`) < v[c] , no excitation can be created and the impurity moves through the medium without dissipation, as if the viscosity is 0, characterizing a superfluid. This is the Landau criterion for superfluidity.

     

    b) Show that when the atom-atom interaction constant G >= 0 (repulsive interactions), this value v[c] is equal to the group velocity of the excitation (speed of sound in a condensate).

    Solution

       

     

    References

    NULL

    [1] Suppression and enhancement of impurity scattering in a Bose-Einstein condensate

    [2] Superfluidity versus Bose-Einstein condensation
    [3] Bose–Einstein condensate (wiki)

    [4] Dispersion relations (wiki)

     


    Download QuantumMechanics3.mw   QuantumMechanics3.pdf

    Edgardo S. Cheb-Terrab
    Physics, Maplesoft

    As a reminder, we regularly host live webinars on a variety of topics for our customers, and we wanted to make this information available to the MaplePrimes community as well.

    This featured webinar for this month will outline the Finance Package in Maple 18 including capabilities like the mathematical, statistical, and connectivity tools required to analyse data, calculate forecasts, estimate risks, prototype and develop quantitative algorithms, and leverage parallel programming techniques.

    Other topics include:

    • Data feed connectivity and system integration

    • Price equity and interest rate derivatives

    • Populate reporting tools, deliver documents and share worksheets

    • Optimize portfolios of financial instruments

    • High-Performance Computing (HPC)

    To join us for the live presentation, please click here to register.

    I'll start with a quick positive.  One of the great advantages of upgraded software is the wealth of new features that we all get to play around with.  .. and then I will counter that with a great disadvantage, and that is, we all just about get familiar and comfortable with all the new features then BAM! a new version is released.  Of course we're then mesmorized once again by all the new bells and whistles and maybe even a couple of great celebrations occur with nice small updates throughout the year.  The other downside is that even though a large number of bugs may have been fixed a number of new ones are broght in with those new features. 

    A side effect of a fast release is there are fewer and fewer applications associated with a release, and that is apparent in the application center.  Although mobius apps and the maple cloud may have also had some impact on that as well.

    Now this is pale in comparison to book writers who scramble to keep their books current with new software.  I will quote a section from the introduction in the book Essential Maple 7 which highlights the problems the author had way back then .. I can't imagine how they feel now but here's the passage ...

    "Indeed, one reason that there was so much time between the first and second
    editions of this book is precisely that Maple has been evolving so rapidly in the
    last few years, too rapidly for me to revise this book (much less complete my
    others) while coping with my other duties."

    That just hits the nail on the head, if you think Maple was evolving fast back then, the furious rate that upgrades are released now I would think authors have an almost impossible task to keep up. 

    There are many that would agree with the author, that Maple is advancing so rapidly that we barely have time to gather our thoughts.  Maybe a solution is that we should slow down and create a much more polished piece of software, but again the caveat to that is our competition might just jump out in front.  However the norm today is that each new year represents a new release of software and we all celebrate when that happens.  If life seemed rushed back when Maple 7 was released I can't imagine what it'll be like 10 years from now when Maple 28 rolls around. 

    Addition, subtraction, scalar product, vector, projections and graphs with physics packages and plots. With this you can begin to start the physics course for engineering.

    Operaciones_con_Vect.mw   (in spanish)

     

    Lenin Araujo Castillo

    Physics Pure

    Computer Science

    Greetings to all.

    I would like to share a brief observation concerning my experiences with the Euler-Maclaurin summation routine in Maple 17 (X86 64 LINUX). The following Math StackExchange Link shows how to compute a certain Euler-MacLaurin type asymptotic expansion using highly unorthodox divergent series summation techniques. The result that was obtained matches the output from eulermac which is definitely good to know. What follows is the output from said routine.

    > eulermac(1/(1+k/n),k=0..n,18);
         1       929569        3202291        691                O(1)
    O(- ---) - ----------- + ----------- - --------- + 1/1048576 ----
         19             15            17          11              19
        n      2097152 n     1048576 n     32768 n               n
    
                                               n
                                              /
            174611      5461        31       |      1           17        1
         - -------- + --------- + ------- +  |   ------- dk - ------- + ------
                 19          13         9    |   1 + k/n            7        5
           6600 n     65536 n     4096 n    /                 4096 n    256 n
                                              0
    
             1       1
         - ------ + ---- + 3/4
                3   16 n
           128 n
    

    While I realize that this is good enough for most purposes I have two minor issues.

    • One could certainly evaluate the integral without leaving it to the user to force evaluation with the AllSolutions option. One can and should make use of what is known about n and k. In particular one can check whether there are singularities on the integration path because we know the range of k/n.
    • Why are there two order terms for the order of the remainder term? There should be at most one and a coefficient times an O(1) term makes little sense as the coefficient would be absorbed.

    You might want to fix these so that the output looks a bit more professional which does enter into play when potential future users decide on what CAS to commit to. Other than that it is a very useful routine even for certain harmonic sum computations where one can use Euler-Maclaurin to verify results.

    Best regards,

    Marko Riedel

     

    It seems that

     

    Limit(N+(sum((-1)^n*Sum(1/n^x, x = 1 .. N), n = 1 .. infinity)), N = infinity)=log(2)

     evalf(300+sum((-1)^n*(Sum(1/n^x, x = 1 .. 300)), n = 1 .. infinity), 30)

    gives

    0.693147180559945309417232121.

     sum(1/n^x, x = 1 .. infinity)

    gives

    1/(n-1).

    In Maple 18, the Database package has been updated to include support for SQlite databases as well as a new option for plots to change the background images on plots.  To showcase both of these features, our engineering team put together an example that optimizes the flight path of a pan-US delivery drone.

    This application extracts the latitude and longitude of those zip codes from an SQLlite database (the application includes the database, which cross-references US zip codes against their latitude, longitude, city and state). The application then performs a traveling salesman optimization and plots the shortest path on a map of the US.

    To download the application click here: PanUSDeliveryDro.zip

    This is a 5-days mini-course I gave in Brazil last week, at the CBPF (Brazilian Center for Physics Research). The material will still receive polishment and improvements, towards evolving into a sort of manual, but it is also interesting to see it exactly as it was presented to people during the course. This material uses the update of Physics available at the Maplesoft Physics R&D webpage.

    Mini-Course: Computer Algebra for Physicists

     

    Edgardo S. Cheb-Terrab

    Maplesoft

     

     

    This course is organized as a guided experience, 2 hours per day during five days, on learning the basics of the Maple language, and on using it to formulate algebraic computations we do in physics with paper and pencil. It is oriented to people not familiar with computer algebra (sections 1-5), as well as to people who are familiar but want to learn more about how to use it in Physics.

     

    Motivation

     

     

    Among other things, with computer algebra:

     

    • 

    You can concentrate more on the ideas (the model and its formulation) instead of on the algebraic manipulations

    • 

    You can extend your results with ease

    • 

    You can explore the mathematics surrounding your problem

    • 

    You can share your results in a reproducible way - and with that exchange about a problem in more productive ways

    • 

    After you learn the basics, the speed at which algebraic results are obtained with the computer compensates with dramatic advantage the extra time invested to formulate the problem in the computer.

     

    All this doesn't mean that we need computer algebra, at all, but does mean computer algebra can enrich our working experience in significant ways.

    What is computer algebra - how do you learn to use it?

       

    What is this mini-course about?

       

    What can you expect from this mini-course?

       

     

    Explore. Having success doesn't matter, using your curiosity as a compass does - things can be done in so many different ways. Have full permission to fail. Share your insights. All questions are valid even if to the side. Computer algebra can transform the algebraic computation part of physics into interesting discoveries and fun.

    1. Arithmetic operations and elementary functions

       

    2. Algebraic Expressions, Equations and Functions

       

    3. Limits, Derivatives, Sums, Products, Integrals, Differential Equations

       

    4. Algebraic manipulation: simplify, factor, expand, combine, collect and convert

       

    5. Matrices (Linear Algebra)

       

    6. Vector Analysis

       

    7. Tensors and Special Relativity

       

    8. Quantum Mechanics

       

    9. General Relativity

       

    10. Field Theory

       

    BrasilComputacaoAlgebrica.mw.zip

    BrasilComputacaoAlgebrica.pdf 

    Edgardo S. Cheb-Terrab
    Physics, Maplesoft

    We regularly host live webinars on a variety of topics for our customers, and we wanted to make this information available to the MaplePrimes community as well. We will be posting information about new webinars we think will be of interest approximately once per month.

    Partnering with the MAA to Revolutionize Placement Testing

    In this webinar, we will demonstrate how the Maple T.A. MAA Placement Test Suite can be used to ease the problem of placement testing and how it can benefit your campus in general.

    Other topics include:

    • How placement testing contributes to student success

    • How the MAA placement tests are created, and rigorously validated

    • How valid and reliable the MAA placement tests are for entry level mathematics courses

    • How you can use the Maple T.A. Placement Test Suite for easy administration, flexible delivery, and fast results

    To join us for the live presentation, please click here to register.

    At the user stored question list for every user stored at maplesoft, all posted dates are correct however at mapleprimes the dates start at April 2010 ???

    Also, unfortunately the question list at maplesoft seems to all end Oct 2013.  I'm not really sure what happened there.  But when I'm trying to search for something I qustioned or posted after Oct 2013 from that list is not going to happen.

    That list was the best thing!  All of your questions and posts ever created are in chronological order making it quite easy to locate a question you were looking for.

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