The background of my question comes from graph theory. But the essence of the problem has nothing to do with graph theory, and it only involves programming.

For the graph g1 below, the paired crossing edges  are marked as wine red.

For each pair of crossed edges, I choose one to delete and get a plane graph g1', and then I consider the edge connectivity of g1', if the edge connectivity is equal 3, stop the calculation and return to the deleted edge set, otherwise continue to look for.

The following code is my attempt, break does not seem to work.

My idea is that as long as the edge set that meets the condition appears for the first time, it should stop. If none are satisfied, return "not found".

Another question：

The above is just my example. In fact, the graph I want to consider is more complicated. If there are 18 pairs of crossing edges, do I need to write 18th-order for-loops? This seems very troublesome. Is there an easier way? Maximum number of for loops is 2^18 that is equal to 262144, which is still acceptable.

In Maple, when calling LinearAlgebra:-Eigenvectors the order can change randomally each time. Ofcourse the result is always correct, but can show up in different order. 

I find this confusing, as I am looking at the screen, and see order changed each time. This is the order of how Maple shows the eigenvalues and corresponding eigenvectors.

Why does Maple do this? Is there a way to have same order given each time? Here is an example. If you run this code twice, most likely you will get different order each time. If not, try the command one more time.

restart;
Sy:=1/sqrt(2)*Matrix([[0,-I,0],[I,0,-I],[0,I,0]]);
lambda, v :=LinearAlgebra:-Eigenvectors(Sy);

screen shot

I thought there might be a global option to tell Maple not to do this? 

Again, answer is correct each time. I just like same output to show each time, as it is less confusing. Sometimes I think I did something wrong when I see different output show up for same command.

sometimes I get expressions with sqrt(n)/n in them where n is positive integer. I'd like Maple to simplify this to 1/sqrt(n).

So sqrt(2)/2 will becomes 1/sqrt(2). I find this simpler.

Here is an example

v:=Vector([1/2, -1/2*sqrt(2), 1/2]);
simplify(v);
simplify(size);
simplify(v,sqrt);
simplify(v,power);

and tried few other things. 

is there a trick to do this? This is the case where all the expression have actual numerical integers in them (not symbolic), just like the above example. These come from numerical examples. 

Before I put in a change request to make LinearAlgebra:-Equal the "is" of matrix/vector options, I wonder is there something else I should be doing. 

LinearAlgebra_Equal.mw

He intentado utilizar el comando "SolveSteps" y no he podido lograr que se muestre los pasos de la solución, incluso copié el siguiente comando que aparece en la ayuda: SolveSteps([12*x + y = 18, 7*x - 8*y = 32]), donde aparecen una serie de pasos antes de llegar a la respuesta final, pero al escribirlo en la "hoja de trabajo", no me aparece el desarrollo del ejercicio, sino que el mismo comando y la ecuación que escribí. Acaso debo de instalar los comandos, será que no vienen predeterminados, o será porque tengo una versión temporal de 15 días, que no permite utilizar dichos comandos?

Gracias por su ayuda.

Hello MaplePrimes, 

So, I have used the discont=true option in the past and it has worked fine for me but for some reason with these functions I am using now the plots are still containing the veritcal asymptotes. Anyone spot something I am forgetting or doing incorrectly?

I have attached my maple file for easy viewing. 

Thanks. 

DiscontQuestion.mw

Hello,

How i use maple to get the formal solution of this non autonomous system :

dsys := {diff(x(t), t) = (a*p*S/h + (-o - u))*x(t) + f(t)*p*S*y(t)/h, diff(y(t), t) = a*(1 - p)*S*x(t)/h + (f(t)*(1 - p)*S/h - b)*y(t)}

I tried dsolve(dsys) but maple consider the set of solution with x(t) y(t) and f(t), but f(t) is a parameter of the system. I search a solution for x(t) and y(t).

Thank you

I easily found the roots of the following equations,

I accidentally discovered that  2*cos((2*Pi)/7) is also the root of this equation. 

0

It’s easy to know that 2*cos((2*Pi)/7) is equivalent to the third root found above

         s := -1.801937736, -0.4450418679, 1.246979604

                          1.246979604

Maybe I don’t like the use of imaginary units, and I prefer  2*cos((2*Pi)/7) .

In the case that I don’t know that  2*cos((2*Pi)/7) is the solution of the equation, can I make a certain transformation without using the imaginary unit to represent the real number. For example, trigonometric functions, exponential functions, etc.

I tried to use the following functions, all failed.

What is interesting is the following phenomenon. Even if Zeta function does not look great:

For this example, can all roots be transformed into trigonometric expressions by maple.

Can someone please tell me why is my output not ''-cos(x) '' but this:

And how can I set up the worksheet to give me the outputs I want?

Few months ago, someone was kind enough to send me an email letting me know that in Maple 2021 the following new change will be in Object

I am attending a workshop on OOP.  In Maple 2021, one will be able 
to invoke a method of an instance of an object with the  syntax:  object_name:-method_name

However, I am not able to get the above to work in Maple 2021. And I looked at the help pages and see no such example. This is what I tried

restart;
module person()
    option object;
    local name := "me";   

    export get_name::static := proc( self::person, $ )
        self:-name;
    end;

    export set_name::static := proc( self::person, name, $ )
        self:-name:=name;
    end;

end:

p:=Object( person ); #create object

p:-get_name();

Error, invalid input: person:-get_name uses a 1st argument, self (of type person), which is missing

What changes are needed in the above code to be able to use  obj:-method()  syntax?

Or is it possible that this change did not go into Maple 2021?

Hey

I can't find the toolbar for drawing i Maple 2021. 

Can anyone help me? I'm using Macbook.

I try to clik on at picture but I can't see it.

I try to insert a drawnig but I can't see it.

Hope someone can help me.

I would like to use the command "TensorArray"  to create the contravariant tensor.  As seen in the following simple routine, the command output seems to assign values to the contravariant tensor, but, on the last line, the contravariant value is still unassigned. 

Hello,

I have solved a differential equation from which I get a solution that contains special functions

BesselK(a1,b1) but also BesselK(a2,b2) and many time the same function but with different parameters

Now I would like to study asymptotics of the solution for small argument of the BesselK functions.

So I would like to replace each BesselK(x,y) (for any x and y) function by the corresponding small argument asymptotics 1/Gamma(x)*(y/2)^(-x)

Is that possbile or do I have to replace each of them manually?

Thanks in advance

Hi,

I am using Maple 13, 16 and 17 on 64 bit ubuntu 14.04LTS without 

any problems.

I tried to start the above Maple versions after upgrading to ubuntu 18.04LTS. Unfortunately, Maple does not start and transmits an incorrect hostid error message. The error message for Maple 16 is pasted below.

The command ifconfig -a produces an ethernet address 00:21:70:a6:a4:4b that is identical to the hostid given in the license.dat file.

I believe that the license manager flexnet is 32 bit. I used the synaptic 

manager to install lsb-base and ia32-libs (synaptic package manager refused to install lsb-core and transmitted some error messages). However, this did not help and I obtained the same hostid error message.

I do not know what is causing the hostid error message. Maybe some script file/s in the Maple installation can be modified such that Maple starts correctly?

Any assistance in getting Maple 13, 16, 17 to start on ubuntu 18.04LTS 

would be much appreciated.

Thank you very much for your support.
CF

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 

> ...:~/maple> maple16
> Maple initialization error, Invalid host.
> The hostid of this system does not match the hostid
> specified in the license file.
> Feature: Maple16
> Hostid: 002170a6a44b
> License path:
> /home/apps/maple16/toolbox/MapleSim/license/MapleSim.dat:/home/apps/maple16/license/license.dat:
> FLEXnet Licensing error:-9,57
> For further information, refer to the FLEXnet Licensing documentation,
> available at
> "https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fwww.acresso.com&c=E,1,5ci9cywR8uvrXaVJ4IkoXH0TFBBbJwSK_TulrfrUDs5AyVQ4TXsHOVm5KWKAIhp4OZb9C4OAnmgylY1JC6fpbdZK9SjQLVrW012Uzxq18iDYC56NG2eDyHS8RPA,&typo=1".
.......
>
> root@<mailto:root@>...:~# ifconfig -a
> enp0s25: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
> ether 00:21:70:a6:a4:4b txqueuelen 1000 (Ethernet)
> RX packets 0 bytes 0 (0.0 B)
> RX errors 0 dropped 0 overruns 0 frame 0
> TX packets 0 bytes 0 (0.0 B)
> TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
> device interrupt 22 memory 0xf6ae0000-f6b00000
>
> lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
> inet 127.0.0.1 netmask 255.0.0.0
> inet6 ::1 prefixlen 128 scopeid 0x10<host>
> loop txqueuelen 1000 (Local Loopback)
> RX packets 454 bytes 35138 (35.1 KB)
> RX errors 0 dropped 0 overruns 0 frame 0
> TX packets 454 bytes 35138 (35.1 KB)
> TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
 

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%