Dear Maple users

I am just curious about how far Maplesoft is updating the Mac version of Maple to 64 bit (Catalina). This version of the Mac OS will hit the shelves in late September this year. As I have been told, no program built on 32 bit will be able to run on this new version of Mac OS. I am pretty sure there will be a lot of software troubles for students upgrading to this version. We can recommend the students not to upgrade immediately, but it would be interesting to hear how far Maplesoft is creating a 64 bit Maple-installer for Mac?

Regards,

Erik V.

Dear Maple users

I have a question about performing operations on a matrix and another one about retrieving information from a matrix. I am looking for the easiest (hopefully also the shortest) way to do it:

1. Given a matrix with several rows and columns. I want to permute the rows in such a way that the entries in a specific column are ordered (either ascending or decending as wished).

2. Given a matrix with several rows and columns. I want to count how many entries in a specific column are above a certain given fixed value.   

I am pretty sure some of you guys out there can do it in an elegant way. Examples will be appreciated.  

Regards,

Erik

Dear Maple users

I could probably make the things happen in an ad hoc way myself, but I am pretty sure there is a smart and conceptual way to do it in Maple, which will make things much easier. That's why I am asking you. 

I am trying to create a Random Variable X build on the outcomes of throwing two dice, i. e. X is a function from the Sample Space consisting of all 36 different 2-tuples of the kind (x,y), onto the Real Numbers. Let's say the dice are colored: one green and one red. The outcome (3,2) means that the green die is displaying 3 dots and the red die is displaying 2 dots. The Random Variable can be any function on that Sample Space: The sum of the number of dots, the square of the number of dots on the green die plus the number of dots on the red die, or it could be something completely different. In this example X will have a finite number of possible values: x1, x2, ..., xn. Now I would like to create such a Random Variable in Maple in a convenient way. Afterward I would like Maple to throw dice by random a number of times, say 100,000 times and show me a Histogram or a list of how many times X got the result x1, x2, etc.

I hope someone can help me get going in a problem like the one described above. 

Kind regards,

Erik V.

Dear Maple users

Sometimes I use the Explore command in order to watch how plots containing parameters change when the parameters are changed via sliders. I tried to do the same with an odeplot. I can make it work, but I cannot do it the same way as I use to do with ordinary plots: I like to define the plot outside the Explore command, because those Explore commands can be quite cluttered and hard to overview. It is not that bad in my attached example below. Sometimes I have display commands handling several plots ... 

In the attached file I show first how it works when the odeplot is inside the Explore command, but when I later move it outside, it won't work. Why this difference between ordinary plots and odeplots? Or maybe there is a workaround to make it work having the odeplot command outside ...

Regards,

Erik

odeplots_in_an_Explore_command.mw

Dear Maple users

Some ODE's like the Lotka Volterra system can only be solved numerically. I would like to solve some equations based on the numerical solution to that system. Let the x(t) and y(t) be the solutions to the ODE system. 

Now, obviously it won't work afterwards to write an equation like solve(x(t)=60,t), since the solution of the ODE only exists as a procedure. Of course I can make an odeplot and zoom in to get an approximate solution to x(t)=60. I would however like it to done automatically. How is this done in the most convenient way when the soltuion of the ODE is given as a procedure?

Example attached. 

Regards

Erik

Lotka_Volterra.mw