I need to automatically extend or truncate a colour list to suit number of points in plottools:-point plot.
extending the list the colour sequence could be repeated or if the is too awkard just add black.
I can't figure out how to select the list of colours to put into a new list to modify.

This will be inside a plotting procedure.

Download 2024-09-06_Q_Extend_or_Truncate_List_of_Colours.mw

How do I mute the action of an accent applied to a symbol so that the accented symbol is itself an inert object? See the attached example.

How_do_I_make_an_accented_symbol_inert.mw
 

As a newbie in Maple2024, my next step is to try to solve a Diophantine equation. Attempts with isolve failed. It is the famous task B3 from the IMO of 1988:

If for integers x and y the fraction (x^2+y^2)/(1+x*y) is a positive integer, then it is actually a square number.

The solution is well known. But I would like to learn how to use Maple using this example and would like some advice.

Best regards, Alfred_F

I was trying to odetest one of my solutions to this ode when I got this internal Maple error I have not seen before.

Is this a legitimate error? my solution could be wrong ofcourse but strange to get internal error in this case.

Does this happen on earlier versions of Maple?

Download internal_error_PDEtools_NumerDenom_sept_4_2024.mw

Is there a way to re-index an existing dataframe? See attachment for example.

how_do_i_re-index_a_dataframe.mw

Dear Power Users, Dataframes are a powerful tool within Maple. However, when I have 'undefined' in cells "Aggregate" or "DataSummary" does not provide answers. However, when I use "Statistics:-Mean" with the additional option "ignore=true" I can get an answer for one column (see attached worksheet). Adding "ignore" to aggregate apparently does not work. What is the method for ignoring the undefined data? In Excel when a cell is blank it will be ignored. Thank you for any help given.MP_Aggregate.mw

From a discussion about expanding unit expressions with compound units I concluded that expanding derived units such as Newton, Watt, Volt, Tesla,... to SI base units is difficult in Maple.

Unintentionally, I came across a rather simple solution for SI units.

toSIbu := x -> x = Units:-Unit(simplify(x/Unit('kg'))*Unit('kg'));

converts derived SI units to SI base units. It’s the inverse of what the units packages and simplify do (i.e. simplification to derived units).

What makes it maybe more interesting: It also works, again unintentionally, on other units than SI units. If, one day, you come along an erg or a hartree or or a kyne and you cannot guess the SI units convert/units needs, try

toSIbu(Unit('pound'));
toSIbu(Unit('hp'));
toSIbu(Unit('electron'));
toSIbu(Unit('hartree'));
toSIbu(Unit('bohr'));
toSIbu(Unit('barye'));
toSIbu(Unit('kyne'));
toSIbu(Unit('erg'));
toSIbu(Unit(mile/gal(petroleum)));

Maybe handy one day when you do not trust AI or the web.

Download toSIbu.mw

(All done with Maple 2024 without loading any package)

Hello. I am trying to use the Remove() command to remove a column of a dataframe. I applied the command like its shown in the help section and I get an error. I don't see how I am applying this command incorrectly. Where am I going wrong? Below is a screenshot of the error output and the .mw file used to generate the output.

Remove_a_column_from_a_dataframe.mw

I attempted to create a phase plot using the Odeplot command in Maple, but the resulting plot isn't as smooth as I'd like. To improve the smoothness, I tried increasing the numpoints parameter to 20,000, but this resulted in the error message: [Length of output exceeds limit of 1000000]. What adjustments should I make to obtain a smoother phase plot without encountering this error?

restart;
r := 1;
b := 1;
c := 0.01;
a := 0.36;
mu := 0.4;
beta := 0.75;

sys := {diff(x(t), t) = r*x(t) - b*x(t)^2 - c*x(t)*y(t) - beta*x(t)*y(t)/(a + x(t)), diff(y(t), t) = -mu*y(t) + beta*x(t)*y(t)/(a + x(t))};
 
ics := {x(0) = 0.2, y(0) = 0.05};

sol := dsolve(sys union ics, {x(t), y(t)}, numeric, range = 0 .. 20000, maxfun = 0, output = listprocedure, abserr = 0.1e-7, relerr = 0.1e-7)

with(DEtools);
DEplot3d(sys, {x(t), y(t)}, t = 0 .. 20000, [[x(0) = 0.2, y(0) = 0.05]], maxfun = 0, numpoints = 35000, thickness = 1, linestyle = solid);
 

with(plots);
phaseplot := odeplot(sol, [x(t), y(t)], 0 .. 20000, numpoints = 10000, color = red, thickness = 2, axes = boxed, gridlines, title = "Phase-space Diagram");

Download extra_steps.mw

Today in class, we presented an exercise based on the paper titled "Analysis of regular and chaotic dynamics in a stochastic eco-epidemiological model" by Bashkirtseva, Ryashko, and Ryazanova (2020). In this exercise, we kept all parameters of the model the same as in the paper, but we varied the parameter β, which represents the rate of infection spread. The goal was to observe how changes in β impact the system's dynamics, particularly focusing on the transition between regular and chaotic behavior.

Download math_model_eco-epidemiology.mw

Hello,

I'm having trouble updating an old Maple package to work with the latest version of Maple. In the package, there are several commands that modify predefined procedures and then rename them (see the example below). I need to save all these new procedures to a text file so I can further modify them and better understand their functionality. How can I achieve this?

d_remset := subs(`class`=`d_class`,`remseta`=`d_remseta`,`premas`=`d_premas`,op(`remset`)):

remset is a procedure previously defined.  

Many thanks.

Obs.: If you have a better idea on how to deal with the procdures, please let me know. 

Dear power users, I was wondering whether it is possible to import a xlsx file in such a way that the first row of the file is imported as column headers of the dataframe in Maple? Thank you in advance for any help given.

Here is another ode solution by Maple, I am not able to get zero from odetest. 

If someone could come up with a trick or method to verify this, that will be great. I tried all sort of assumptions and not able to get zero. Even coulditbe() could not give zero. 

It is a Chini ode and also homogeneous, `class G`.

Solving using either method, odetest do not returns zero.  There are no initial conditions. I am sure the solutions are correct, but odetest need some help or may be this requires different method to verify not using odetest?

Worksheet below.

Download challenge_odetest_sept_1_2024.mw

What is the correct syntax in Maple to do integration of variables on 

So that the new integration variable is y using the mapping    u=y*x^(1/3) so that the result is 

The problems seems is that there is no option to tell Maple what the new integration variable is. So it does not know it should be y or x?

I looked at help and all my tries failed. Below is worksheet and also examples from another software as reference. The other software has argument to tell change of variable what is the new integration variable should be. But in Maple, there is no such option.,  Does this mean in Maple change of integration variables only works when the right hand side of the transformation has only one symbol and not two or more? i.e. this works   u=y, but not u=y*x

Download change_of_variables_integration_august_31_2024.mw

I searched help and see nothing specific to change of variable for integration, so I assumed the above is the command to use. Am I using the wrong command for integration change of variables in Maple?

For reference, I need to duplicate this in Maple:

If there any way to make text  parallel to a line in textplot3d.

display(line([1,2,3],[4,5,-2],linestyle=longdash),
        point([2.5,3.5,0.5]),
        textplot3d([2.5,3.5,0.5,"not aligned"]))