Hello!

I am currently working with the A = rosser Matrix. Which is found in Matlab. The task is to find the eigenvectors of this Matrix in Matlab and Maple. I have succeeded in matlab, but I am confused with Maple. What I have done:

1) In Matlab I save the A = roseer so I could import in from Maple

2) I go back to Maple

3) I write with(LinearAlgebra);

3) I use this path "Tools>Assistants>Import Data" and I select the saved Matlab file (Named A.mat) (No specific folder if that is important)

4) I use "Matrix Data Type" as "Anything" and I give the Variable name "A"

5) I now see the Matrix inside Maple. BUT I get dots after each value. Like this --> 99. 3. -147. etc - This might be an issue.

Note: I never get to select file format. Is that because they know it was a matlab file? Or a setting I am missing out on?

6) I write A := A[2] (According to teachers instructions)

7)  Then I write: eigenvects(A);  (Teachers isntructions)

But I am getting no proper values at all. I assume it is something with the import. So I added this 8x8 Matrix by hand. I got a better result with a result. But the result is wrong. I am getting 7 eigenvectors while there should be 8. See the code at: Method-two.mw

I am turning crazy over here. Anyone smart who could help me out please?

Hi,

I use Statistics[Biplot] and the rendering is very bad with those huge arrows.

For the moment I fix this by modifying the definitions of the curves which draw each arrow (after using getdata to recover the Biplot structure)

Does it exist a simpler way to manage the appearance of the arrows ?
(options cb, cw and ch of plottols[arrow] are incorrect in Statistics[Biplot](..., arrow=[...]).

Thanks in advance

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!

Hello,

I used the interface(typesetting = extended) command to change the notation used for time derivative of o variable.

But it doesn't seem to be working well when the variable is in the supercript form (check the last line).

How can I solve this issue?

Mapleprimesquestion.mw

x/2 seems completely wrong as a CDF. In other cases Maple correctly writes the CDF as a piecewise-constant function clipped to 0..1:

with(Statistics):

dd := Distribution(ProbabilityFunction = 1/2, Support = 1 .. 2);

PDF(dd, x); # OK
                   (1/2)*Dirac(x-1)+(1/2)*Dirac(x-2)

CDF(dd, x);
                                (1/2)*x

Also CDF seems to have issues with DiscreteValueMap specified using a list, a table or piecewise():

dd := Distribution(ProbabilityFunction = 1/2, DiscreteValueMap = (n -> [1, 2][n]), Support = 1 .. 2);

PDF(dd, x); # OK
                    (1/2)*Dirac(x-1)+(1/2)*Dirac(x-2)

CDF(dd, x); # indeterminate
  int((1/2)*Dirac(0)*Dirac(_t-1)+(1/2)*Dirac(0)*Dirac(_t-2), _t = -infinity .. x)

Download DiracMatricesAndPerformMatrixOperation.mw

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

i have system of ode, which has three unkonwn function,x(t),y(t),z(t), and i need differentiation of theses function with respect to " t " , how can i use numeric solution to have these parameters? tnx for help in advance

 

Download question.mw

Hello everyone!

I have several problems with listcontplot.

First of all, when I plot spectrogram of my test signal I get correct result. I use colorscheme = ["#00007F", "Blue", "#007FFF", "Aqua", "#7FFF7F", "Yellow", "coral", "Red"] as colormap. But I can't understand how to set option coloring in listcontplot correctly to obtain same result, because coloring works as Gradient from ColorTools.

Secondly, I use subs to change plot ranges. My apprach consist in several steps:

plot( listdensityplot(...) );
temp := plottools:-getdata(%, 'rangesonly');
subs(temp[1] = NewX0 .. NewX1, temp[2] = NewY0 .. NewY1, listdensityplot(...) );

Is it possible to simplify this solution?

P.S. My test programm with test data.

Maple_s_test.mw

Test.txt

My Spectrograms:

Hi,

With exam period coming closer and closer I am getting worried that this (see picture) might happen again with my document. The document is completed "deconstructed" all the way through, it contains it unreadable form when exported as PDF and when opened from another device.

Does anybody know what has gone wrong and what to do?

Thankyou,

Emma

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

Suppose that I make a simple plot, of a function f(x), such as  p1 := plot( 2*x+1,x=0..4,numpoints=9);

Then logically, the plot p1 contains a table with values (x, f(x)) which are plotted.

HOW can I extract that table of values from the plot p1, and write it to a data file (simple text file), so that I can process the data elsewhere (for example, for making a professional graph from them).

I had scripts who did this up to Maple 13 (or Maple V release 13, if that is the politically correct version), but they do not work anymore with more recent versions.

Many thanks !!

Malte.

first question:

Define a two point distribution:
f1(x):=piecewise(x = 0, 0.3, x = 0.1, 0.7, 0)

Dist1 := Distribution(PDF = f1)

R1 := RandomVariable(Dist1)

Mean(R1)

Why Mean(R1) gives 0? should be 0.07...

If I managed to define antother discrete point distribution say R2. Can I define R:=R1+R2 and then caculate Mean(R) or even plot PDF of R?

I solved a system of differential equations and want to declare an integral with variable upper limit ( T(x) ) from a function I got from the system ( r(x) ). I did so, but Maple doesn't recognise it as a function of one variable, because when I put this T(x) into a system, it gives me an error:

Error, (in dsolve/numeric/process_input) input system must be an ODE system, got independent variables {t, x}

Though there is no t in the system, t was an integration variable when I declared T(x).

Where is the mistake?

2.mw

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