My co-author and I recently published the 3^rd edition of our finite element book¹ utilizing routines written with MAPLE. In this latest edition, we include a chapter on the meshless method. The meshless method is a unique numerical method for solving PDEs. The finite element method requires the establishment of a mesh associated with node points. Consideration must be given in establishing a good mesh (and minimizing the bandwidth associated with node numbering). The meshless method does not require a mesh to connect nodes. The following excerpt describes the application of the meshless method for a simple 1-D heat transfer simulation using six nodes.

> restart:
   with(LinearAlgebra):with(plots):

# MESHLESS METHOD SOLUTION USING MULTIQUADRIC RADIAL BASIS
FUNCTIONS (RBF) il:=6:To:=15:TL:=25:L:=1:
>   x:=[0,1/5,2/5,3/5,4/5,1]:
>   S:=1000:n:=1:dx:=1/(il-1):
>   C:=Array(1..il,1..il):phi:=Array(1..il,1..il):d2phi:=Array(1..il,1..il):
b:=Vector(1..il):TM:=Vector(1..il):alpha:=Vector(1..il):
for i from 1 to il do
   for j from 1 to il do
      phi[i,j]:=(1+(x[i]-x[j])^2/(S*dx^2))^(n-3/2):
      d2phi[i,j]:=3*((x[j]-x[i])/20)^2/(4*((x[j]-x[i])^2/40+1)^(5/2) )-1/(40*((x[j]-x[i])^2/40+1)^(3/2)):
   end do:
end do:
>   for i from 2 to il-1 do    
>       for j from 1 to il do
>         C[i,j]:=d2phi[i,j]+phi[i,j];
            b[i]:=-x[i];
>         C[1,j]:=phi[1,j];
           C[il,j]:=phi[il,j];
         end do:
      end do:
      b[1]:=To:b[il]:=TL:
> #ConditionNumber(C);
>   alpha:=LinearSolve(convert(C,Matrix),b):
TM[1]:=To:TM[6]:=TL:
for i from 2 to il-1 do
   for j from 1 to il do
>         TM[i]:=TM[i]+alpha[j]*(1+(x[i]-x[j])^2/(S*dx^2))^(n-3/2);
 >     end do:
>   end do:
     evalf(TM);

                     

> TE:=To*cos(xx)+(TL+L-To*cos(L))/sin(L)*sin(xx)-xx:
> TE:=subs(TE):
> TE:=plot(TE,xx=0..1,color=blue,legend="Exact",thickness=3):
> MEM:=[seq([subs(x[i]),subs(TM[i])],i=1..6)]:
> T:=plots[pointplot](MEM,style=line,color=red,legend="MEM", thickness=3): 
  MEM:=plots[pointplot](MEM,color=red,legend="MEM",symbol=box, symbolsize=15):

>  plots[display](TE,MEM,T,axes=BOXED,title="Solution - MEM");

              

Just over a year ago, someone asked me if Maple could help them pick names for their family gift exchange, because they were fed up with trying to find a solution by hand that met all their requirements. I knew it could be done, of course, and I spent some time (and at least one family dinner conversation) talking about how to do it. There wasn’t enough time to help my friend last year, but I dusted off my ideas, and my somewhat rusty Maple programming skills, and put something together for this year.

The problem, as stated to me, was “Assign everyone in the group the name of someone else in the group (the person they will buy a present for), with the restriction that no one can be assigned their partner.”

I decided to generalize a bit so that you can specify more than one person in the “do not pick” list for each individual, and the restrictions do not have to be reciprocal. That way, you can use it with rules like “parents cannot pick their children”, or “Elizabeth got Martin two years running, so she can’t pick him again this year”.

Ultimately I went with a “guess and check” approach. For each person, pick a name from the pool of suitable candidates (excluding themselves, anyone on their “do not pick” list, and anyone who has been picked already). Keep assigning names until either everyone has a name, or you end up in a situation where you can’t give someone a name. This can happen, for instance, if Todd is the last name, and the only unmatched name is Catherine, and Todd cannot pick Catherine. If that happens, I tossed all the names back into the virtual hat, gave it a good shake (i.e. randomize()) and tried again. Not as elegant as I would have liked, but it seemed like an effective approach.

It does feel like there ought to be a “nicer” solution. Maybe using graph theory? I know that my code will get into trouble if the restrictions are such that no solution exists.  If anyone has any ideas on other/better ways to solve this problem I’d be happy to hear them (now that I’ve had the fun of solving it myself first!).  

The application can be found on the application center: Gift Exchange Helper. The name picker algorithm is in the start-up code.

Happy gift giving!

Download DiracMatricesAndPerformMatrixOperation.mw

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

Are you a broke university or college student, living day to day, sustaining yourself on a package of ramen noodles every day? Scared that you’re missing necessary nutrients? Well this is the Maple application for you!

This app, refurbished and modified to fit the budget and nutritional needs of a student, based on this older app: https://www.mapleprimes.com/maplesoftblog/34983-The-Diet-Problem, takes a list of more than 20 foods, and based on nutritional and budget constraints that you choose and can change, will give you the cheapest option for foods that fits your needs!

Maybe you’re not a broke student, but rather someone who wants to keep track of calorie intake or macronutrient intake on a daily basis, well then this app still works for you!

Find it here:
https://www.maplesoft.com/applications/view.aspx?SID=154368

Application to generate vector exercises using very easy to use patterns. These exercises are for sum of vectors in calculations of magnitude, direction, graph and projections. Basically to evaluate our students on the board and thus not lose the results. For university professors and engineering students.

Generator_of_exercises_with_vectors.mw

Lenin Araujo Castillo

Ambassador of Maple

We added a small new feature to MaplePrimes that will make it easier to tag other members in your questions, posts and comments.

To use the feature, type "@" in a message. If you wait a moment, a list of names will be populated, starting with members who are participating in the current thread, followed by other members ordered by reputation. You can also begin to type after the "@" to search for a particular member. Similar to the above, members who match your search who are in the current thread will appear first, followed by others.

If you are tagged in this way, an indication will appear in your notifications pane.

We hope you find this new feature useful!

Many of you enjoyed our profile on one of our developers, Paulina Chin, so we’re happy to bring you another one!

Today, we’ll be talking with John May, Senior Developer of Maple. Let’s get started.

1. What do you do at Maplesoft?
   Until recently I was consulting on-site at the NASA Jet Propulsion Laboratory helping people there more effectively solve their engineering problems using Maplesoft products.  But my main job that I am back to full time now is the development and maintenance of various parts of the Maple library.
    
2. What did you study in school?
   I studied both Pure and Applied Mathematics at the University of Oregon,  focusing a lot on Abstract Algebra.  In graduate school, I specialized more in computation mathematics like computer algebra and numerical analysis.  My Ph.D. work focused on effective numerical algorithms for problems in polynomial algebra – with implementations in Maple!
    
3. What area(s) of Maple are you currently focusing on in your development?
   Right now I am focused on addressing complaints I’ve gotten from engineers about the usability of units with other parts of the math library.
    
4. What’s the coolest feature of Maple that you’ve had a hand in developing?
   A lot of the cool things I’ve built live pretty deep in the internals of Maple.  I’ve done a lot of meta-heuristic tuning to seamlessly integrate high-performance libraries into top-level Maple commands.
   
   I had a lot of fun developing a lot of the stuff for manipulation and visualization of colors in the ColorTools package.
    
5. What do you like most about working at Maplesoft? How long have you worked here?
   I started working at Maple in 2007, but I’ve been a Maple user since 1997.  I love being part of the magic that brings powerful algorithmic mathematics to everyone.  The R&D team is also full of eccentric nerds who are great fun to work with.
    
6. Favourite hobby?
   It varies by the season, but right now it is prime for mountain biking in southern California.  I ride my local trails a couple times a week, and when I get I chance, I love to get away on epic bikepacking adventures (like this one: https://www.bikemag.com/features/two-wheeled-escape-one-hour-from-l-a/  this is me: https://cdn.bikemag.com/uploads/2016/05/16File.jpg ).
    
7. What do you like on your pizza?
   Anything and everything. Something different every time. My all-time favorite pie my from grad school days is the “Rio Rancho” from the dearly departed That’s Amore Pizza (which was next to the comic book store and across the street from North Carolina State University).  It was an olive oil and mozzarella pizza with chopped bacon that was covered in sliced fresh roma tomatoes and drizzled with ranch dressing when it came out of the oven. 
    
8. What’s your favourite movie?
   It’s really hard to pick just one.  So, I’ll go with the safe answer and say the greatest movie of all time, and “Weird Al” Yankovic’s only foray into movies, UHF, is my favorite.
   http://www.imdb.com/title/tt0098546/
    
9. What skill would you love to learn? (That you haven’t already) Why?
   Another hard one.  I feel like I’ve dabbled in lots of things that I would like to get better at.  At the top of the list is probably unicycling.  I’d love to get good enough to play Unicyle Football or do Muni (mountain unicyling).
   https://en.wikipedia.org/wiki/Mountain_unicycling
   http://www.unicyclefootball.com/
    
10. Who’s your favourite mathematician?
    Batman. https://youtu.be/AcMEckOyoaM

The Perimeter Institute for Theoretical Physics (PI) is a place where bold ideas flourish. It brings together great minds in a shared effort to achieve scientific breakthroughs that will transform our future. PI is an independent research center in foundational theoretical physics.

One of the key mission objectives of Perimeter is to provide scientific training and educational outreach activities to the general public. Maplesoft is proud to be part of this endeavor, as PI’s Educational Outreach Champion. Maplesoft’s contributions support Perimeter’s Teacher Network training activities, core educational resources, development of online course material, support of events such as the EinsteinPlus workshop for high school teachers, the International Summer School for Young Physicists (ISSYP), and other initiatives.
 

The annual International Summer School for Young Physicists (ISSYP) is a two-week camp that brings together 40 exceptional physics-minded students from high schools across the globe to PI. The program covers many different topics in physics such as quantum mechanics, special relativity, general relativity, and cosmology. Each year students receive a complimentary copy of Maple, and use the product to practice and strengthen their math skills. The program receives an average of three-hundred applications from students in grades eleven and twelve from around the world. Competition is intense, and students who are chosen for the program are extremely bright and advanced for their age; however there is some variation in their level of math and physics knowledge. . Students are asked to review a “math primer” document to prepare them with the background needed for the program.The ISSYP program now uses Möbius, Maplesoft’s online courseware platform to administer this primer. With Möbius, PI has moved from a pdf document primer to fully online material, which has motivated more students to complete the material and be more engaged in their courses. The interactivity and engagement that technology provides has made the summer program more productive and dynamic.

EinsteinPlus is a one-week intensive workshop for Canadian and international high school teachers that focuses on modern physics, including quantum physics, special relativity, and cosmology. EinsteinPlus also provides unique opportunities to learn some of the latest developments in physics from expert researchers at the forefront of their fields. Maplesoft proudly supports this workshop by giving teachers access to and training in Maple.

Perimeter Institute also organizes a lively program of seminars, regularly exposing researchers and students to current ideas in the wider theoretical physics community. The talks provide content outside of, but related to, core disciplines.  Recently Maplesoft’s own physics expert Dr. Edgardo Cheb-Terrab conducted a lecture and training session at PI on Computer Algebra for Theoretical Physics.

Dr. Edgardo Cheb-Terrab is the force behind the algorithms and Maple libraries of the ODE and PDE symbolic solvers, the MathematicalFunctions package (an expert system in special functions) and the Physics package, among other things.  

In his talk at PI, the Physics project at Maplesoft was presented and the resulting Physics package was illustrated through simple problems in classical field theory, quantum mechanics and general relativity, and through tackling the computations of some recent Physical Review papers in those areas.   In addition there was a hands-on workshop where attendees were offered four choices of activity:  follow the mini-course; explore items of the worksheet of the morning presentation; or bring their own problems so that Dr. Cheb-Terrab could guide them on how to tackle it using the Physics package and Maple in general.

As a company that strives to continuously improve student learning, and empower instructors and researchers with the tools necessary to compete in an ever changing and demanding educational environment, Maplesoft’s partnership with the Perimeter Institute allows us to do just that. We take great pride and joy in bringing our technology to outreach programs for students and teachers, making these opportunities a more productive and dynamic experience for all.

Download DiracAlgebraWithIdentityMatrix.mw

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

Hey guys...

One of my favorite new images rendered in Maple.....

integrates mod congruency arguments like the following, into an 8 stage animated 3D cylindrical coordinates context::

u*mod(x^(1/3)cos(x),23)

As a powerlifter, I constantly find myself calculating my total between my competition lifts, bench, squat, and deadlift. Following that, I always end up calculating my wilks score. The wilks score is a score used to compare lifters between weight classes (https://en.wikipedia.org/wiki/Wilks_Coefficient ), as comparing someone who weighs 59kg in competition like me, to someone who weighs 120kg+, the other end of the spectrum; obviously the 120kg+ lifter is going to massively out-lift me.

So I decided to program a wilks calculator for quick use, rather than needing to go search for one on the internet. For anyone curious about specific scoring, a score of 300+ is very strong for the average gym goer, and is about normal for a powerlifter. A score of 400+ makes you strong for a powerlifter, putting you in the top 250 powerlifters, while 500+ is the very top, as far as unequipped powerlifting goes, including the top 30. For anyone wondering, my best score at my best meet was 390, although given the progress I’ve made in the gym, should be above 400 by my next meet.

Hope you all enjoy!

 Find it here: https://maple.cloud#doc=5687076260413440&key=301A440EFD2C4EDD8480D60B5E3147BF40CA460F842942449C939AB8D2E7D679

The problem is to analyze the behavior of an involute of the cubical parabola near the singular points and at infinity.

To do this efficiently, it is best to work with partially evaluated expressions.

Download cubic.mw

I submit a bug through MaplePrimes because I can't do it as usually (Hope some people understand me.). Let us consider

with(LinearAlgebra):
M := Matrix(5, 5,  (i, j) -> (10*i+j)*sin((1/180)*Pi*(10*i+j))):
MatrixInverse(M);
 #One sees a long and wrong output instead of the warning "Matrix M is singular"

Indeed,

Digits := 500; evalf(Determinant(M), 495);
                               
                           1.3 10 ^(-488)   

Bug_in_MatrixInverse.mw

I submit a bug through MaplePrimes because I can't do it as usually (Hope some people understand me.). Let us consider

restart; pdsolve([diff(u(t, x), t, t) = diff(u(t, x), x, x), u(t, 0) = 0, u(t, Pi) = 0]);
pdsolve([diff(u(t, x), t, t) = diff(u(t, x), x, x), u(t, 0) = 0, u(t, Pi) = 0], generalsolution);
u(t, x) = Sum(sin(n*x)*(_C5(n)*cos(n*t)+_C1(n)*sin(n*t)), n = 1 .. infinity)
u(t, x) = Sum(sin(n*x)*(_C5(n)*cos(n*t)+_C1(n)*sin(n*t)), n = 1 .. infinity)

The question arises: what do these outputs mean? I don't see any explanation in ?pdsolve and ?examples,pdsolve_boundaryconditions. What are _C1(n) and _C5(n)? Under which conditions does the above series converge?

Moreover,

pdetest(%, [diff(u(t, x), t, t) = diff(u(t, x), x, x), u(t, 0) = 0, u(t, Pi) = 0]);
                           [0, 0, 0]

I think the above is simply a fake: it is possible to differentiate  a series only under certain conditions.

Bug_in_pdsolve.mw

Please, don't convert my post to a question. This is not correct and fair. Hope some people understand me.

Inspired by this question. There is a simple iterated procedure that can generate the Puiseux expansion.

Download np.mw