## Can Maple import the graphs generated by nauty or ...

I've been asking a similar question：

How does Maple call external programs such as nauty?

Recently I used Mathematica to call these gadgets very succinctly, so I revisit the topic, and maybe Maple can do it as well, but I just didn't do it the right way.

• nauty and Traces are programs for computing automorphism groups of graphs and digraphs. There is a small suite of programs called gtools included in the package. For example, geng can generate non-isomorphic graphs very quickly.
• plantri and fullgen are programs for generation of certain types of planar graph.

We note that binary executables of above two programs for Windows are not officially available. Fortunately, I recently compiled them by cygwin.  Of course, other operating systems can make it easier to use them. See attached two compressed files of compiled nauty and plantri programs for Windows.

The official websites of the two programs are listed below.

So, I found that Mathematica works very well for running these programs by Import. We list the following two examples: first example is to get all non-isomorphic 10-order 2-partite connected graph, and the second example is to get all 14-order non-isomorphic  quadrilateral graphs (the planar graphs in which any face is 4-face).

```glist10 = Import["!D:/nauty27r3/geng -c -b 10", "Graph6"]; // AbsoluteTiming
Length[glist10]```

`g14 = Import["!D:/plantri52/plantri 14 -q -g ", "Graph6"] // AbsoluteTiming`

I tried maple's Import or ImportGraph functions, but both failed.

```restart:
with(GraphTheory):
L:=ImportGraph("!D:/nauty27r3/geng -c -b 10 -g",output=list):
L2:=Import("!D:/nauty27r3/geng -c -b 10 -g"):
```

Error, invalid input: GraphTheory:-ImportGraph uses a 2nd argument, format (of type {string, symbol}), which is missing
Error, (in Import) must specify format for this input

The problem seems to be not recognizing compilations symbols " !".  I don't know if Maple can do this like mathematica.

## Put markers curve ...

Dear all

I need to  `Put markers to emphasize the point of intersection between f, and g

iteration.mw

thank you

## List monomials in a polynomial, each as a coeffici...

Given a polynomial, e.g. 3*x^2 + a*x*y + b*y^2, is there some built-in function which can give me a list of monomials, with each monomial represented as [coefficient, [exponent_of_x, exponent_of_y]] ? The above polynomial would turn into something like [ [3, [2,0]], [a, [1,1]], [b, [0,2]] ].

It's not difficult to write this procedure from scratch. The procedure would require two arguments: (1) the polynomial itself, (2) which symbols are considered variables (in the above case, x and y). The remaining variables, a and b, would then be treated as constants that appear as coefficients. But I'm wondering if there's a built-in function I can just use.

## Solving 2nd order ode with sin and cos terms...

Hi everyone, Could you help me to get a general solution to the following ode? Here rho and z are constants.

 >
 (1)
 >
 (2)
 >

Thanks.

## Benders Decomposition in Maple ...

Does maple software support Benders decomposition technique for Mixed Integer Linear Programming? If no, how we can implement it in maple? Any suggestions.

Thank you

## How to draw Contour plot for the given data...

x := [0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4]

y := [0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4]
z := [0, 0, 0, 0, 0, 0, .689376362, 1.378752724, 2.068129087, 2.757505449, 0, 1.02920355, 2.0584071, 3.087610649, 4.116814199, 0, 1.216469264, 2.432938529, 3.649407793, 4.865877057, 0, 1.325720912, 2.651441823, 3.977162735, 5.302883646]

How to plot the contour plot for the given data

## How can I construct the difference table using the...

Dear Users! Hope everyone is fine here. I have some points x_0,x_1,..,x_N and corresponding to these number have values y_0, _1, ..., y_N as,

restart
a := 1; b := 5; h := 1; f := 1/x; N := (b-a)/h;
for i from 0 while i <= N do x[i] := h*i+a; y[i] := eval(f, x = x[i]) end do;

Now I want to develope the following difference table using the values of y_0, y_1, ..., y_N as,

where difference column generated using the following concept

## How do I solve second order equations and obtain r...

I have been studying the solutions of the equation below using Maple and Mathematica.

$\large 4a_{02}^2+4ka_{02}a_{11}+k^2a_{11}^{2}+4b_{02}^{2}+4kb_{02}b_{11}+k^{2}b_{11}^{2}=0$

Here, I want to express the solutions for k. In Maple, the solution is imaginary. As one may see below.

On the other hand, if one solves that  exact equation with Mathematica, then one has real solutions. That is,

$\large k_{1,2}=\frac{1}{a_{11}^{2}+b_{11}^{2}}2\left(-a_{02}a_{11}-b_{02}b_{11}\pm\sqrt{-a_{11}^{2}b_{02}^{2}+2a_{02}a_{11}b_{02}b_{11}-a_{02}^2b_{11}^2}\right)$

Based on the above, I have a few questions:

1. What is the correct solution for the first equation above? That is, are the solutions real or complex?

2. How may I obtain the real solutions, k_{1,2}, above using Maple?

Attached below you may find my mwfile with my doubts.

Mydoubts.mw

## how to Export plots...

hello,

i want to export Export plots to jpg,

im using the following command (example of the idea) :

>for i from 1 to 5 do

fig:=plot(x*i,x=0..10):
Export("Fig.jpg", plot(sin), base = homedir):
od:

how do i make the export aumaticly change the name of the distany file - like Fig[i] or somthing so it wont run it over each iteration.
writing Fig[i] in the command does not work.

## executing columns in a Table in parallel ...

hello
i have a Table in my worksheet;

it countains 3 coulmns, and each coulmns cointains a loop that requires about a day to evaluate.

is there a way to excute the 3 coulmns in parallel, there is no interaction between them and i cant seprete them into different worksheets.

## delay in typing...

Anyone experience a delay in typing as the screen fills with text/math etc.?

I'm using Maple 2021 and as the space is filled typing slows. I can finish typing and watch the last 4 keys enter on the screen.

## Problem running xmaple 2021.2 in Ubuntu 20.04...

Since approximately a week ago, probably after some Ubuntu update, the xmaple 2021.2 interface started to crash after some simple commands, without any error message or log. I tried to run with java (open-jdk) 11 and 8, and I had the same problem. I still have an old 2017.3 version, and it works perfectly. The problem only affects the new Maple release.

Is there some bug report? What can I do?

## I have a problem with the "Diff" command....

Hi !

Looks like there is a bug in the inert "Diff" command.

I have Maple 2018 on Windows 10 ,64 bits.

Does Maple consider Diff(f(x),x) to be equal to Diff(f(x),[x]) ?

It should be the same.

Maple displays  that it is equal but keeps in memory something else.

In the attached file, I give a very simple example.

I don't like to say this but my old version of Maple V Release V (1997) is more consistent i.e.

this version shows it's different and  keeps in memory that difference.

diff-problem.mw

I wonder if newer versions have this problem ?

Best regards !

## How does fsolve work?...

When using the built-in fsolve function to find the roots of a polynomial, how does exponentiation occur? For example, x3 is found​​​​​​first, and then to find x4, will he start again from the beginning, that is, x*x*x*x, or will he take the value of x3​​​​​​ and multiply by x? The teacher is interested in finding out this, but I don't know how to find out myself.