## difficulties with textplot and polygonplot...

restart;
with(plots): with(geometry):
_EnvHorizontalName := 'x':
_EnvVerticalName := 'y':
a := 7:
point(E, 0, a*sqrt(3)/2):
point(B, -a/2, 0):
point(C, a/2, 0):
point(o, 0, a*sqrt(3)/6):
point(A, 0, a/2):
point(H, 0, 0):
R := (3-sqrt(3))*sqrt(2)*a/12:
point(J, 0, a*sqrt(3)/6 - R):
triangle(Tr1, [E, B, C]):
triangle(Tr2, [A, B, C]):
StretchRotation(E1, E, B, Pi/4, clockwise, sqrt(2)/2);
coordinates(E1);
StretchRotation(E2, E, C, Pi/4, counterclockwise, sqrt(2)/2);
coordinates(E2);
triangle(Tr3, [E, B, E1]);
triangle(Tr4, [E, C, E2]);
triangle(Tr5, [B, C, J]);
circle(cir, [point(P1,[0,a*sqrt(3)/6]), R]):
poly := Matrix([[0, a*sqrt(3)/2], [-7/4 + (7*sqrt(3))/4, -7/4 + (7*sqrt(3))/4], [0, a/2], [7/4 - (7*sqrt(3))/4, -7/4 + (7*sqrt(3))/4]], datatype = float);
pol1 := polygonplot(poly, colour = "Magenta", transparency = 0.7, gridlines);
tex := textplot([0.2, a*sqrt(3)/2, "zE"], 'align' = {'above', 'right'});
draw([Tr1(color = cyan),
Tr3(color = green),
tex,
cir(color=blue),
Tr2(color = red),
Tr4(color = grey),
Tr1(color=blue)],'view' = [-5 .. 5, 0 .. 7],
axes = normal, scaling = constrained,size=[800,800]);
Error, (in geometry:-draw) the option must be of type equation or name
line(L1, [B, o]);
Equation(L1);
line(L1, -(7*x*sqrt(3))/6 + (7*y)/2 - (49*sqrt(3))/12 = 0);
reflection(J1, J, L1);
triangle(Tr6, [B, J1, E]);
line(L2, [C, o]);
Equation(L2);
line(L2, -(7*x*sqrt(3))/6 - (7*y)/2 + (49*sqrt(3))/12 = 0);
reflection(J3, J, L2);
triangle(Tr7, [C, J3, E]);
triangle(T1, [E, J1, A]);
triangle(T2, [E, C, E2]);
triangle(T3, [B, H, J]);
triangle(T4, [C, H, J]);

draw([cir(color = orange, filled = true, transparency = 0.1), pol1, Tr6(color = blue, filled = true, transparency = 0.2), Tr5(color = blue, filled = true, transparency = 0.2), Tr7(color = blue, filled = true, transparency = 0.2), T1(color = green, filled = true, transparency = 0.2), T2(color = green, filled = true, transparency = 0.2), T3(color = green, filled = true, transparency = 0.2), T4(color = green, filled = true, transparency = 0.2)], axes = none, scaling = constrained);
Error, (in geometry:-draw) the option must be of type equation or name
NULL;
NULL;

Why these errors messages ? Thank you.

## Extract subgraphs from a supergraph...

Problem 1)   Give graph G1 and a graph G2  the problem is to extract maximum isomorphic copies of G1 from G2 such that it has no edge intersection maximum number is floor((number of edges of G2)/(number of edges of G1)) and display the Edge sets of those isomorphic graphs and the graph formed by the remaining edges sometimes their may be no remaing edges too.  Need all possible such copies.

Problem 2) Give graph G1 and a graph G2  the problem is to extract maximum isomorphic copies of G1 from G2 such that each copy has  exactly one edge intersection with each of the copies and that one edge intersection occurs only between those two copies and  display the Edge sets of those isomorphic graphs . Need all possible such copies.

I had written this c++ code years back for problem 2 which i have forgotten kind help if possible to make it better with maplesoft.

Please take your time. Kind help help plese it will be very helpful it is of real help.

orthogonal.txt

I had written this c++ code years back for problem 1 which i have forgotten kind help if possible to make it better with maplesoft.

Please take your time. Kind help help plese it will be very helpful it is of real help.

decom.txt

Need to maintain memory space as graph size is a little big may be

would usage of database or any other be useful dont know I had done those code in c++ long back which i forgotten logic too.

I would surely acknowledge for this great work as much as I can much more than I can acknowlege too

I am using Maple 2020

## How can an row Vector be extended?...

I need to conver 2D points to projective points. Originally I used lists but now need to handle vectors too. To add to that that the projective coordinate for points is now being stated as [1,x,y] instead of [x,y,1]. That is was easy enough to handle for lists.

I have a lot of old worksheets that use the list form [x,y,1] that I want to maintain compatibility with. I only have one procedure I need to convert.

```Mobposn := 1;
testP := [2, 7];
if Mobposn = 1 then
[1, op(testP)];
else
[op(testP), 1];
end if;```

I need to do the same for vector definition of the points. The points are defined as row Vectors

`A:=<2,7>^%T`

to get

```Ap:=<1,2,7>^%T

or

Ap:=<2,7,1>^%T```

I know coud just do (as these are short vectors)

```Ap:=<1,A_1,A_2>^%T

or
Ap:=<A_1,A_2,1>^%T```

Is there a more general way?

## Why extracting a n*1 matrix from n*m matrix gives...

I am trying to do the following computation. I  extracted n*1 matrix from n*n matrix which unbelievably gives vector?

How I can do the following multiplication without using convert command? Or how to extract n*1 matrix (not vector) from n*n matrix without using convert?

 >
 >
 >
 >
 >
 (1)
 >
 >
 (2)
 >
 (3)
 >
 (4)
 >
 >
 >
 (5)

## Basins of attraction...

Hello,

I'm trying to draw the basins of attraction for King's method with f(z) = z^3 - 1

## Double Pendulum Linearization...

I'm confused by the state equations resulting from linearizing the DoublePendulum example model.

The state equations are:

diff(x[1](t),t) = x[2](t),

diff(x[2](t),t) = 0,

diff(x[3](t),t) = x[4](t),

diff(x[4](t),t) = 0

where:

x[1](t) = R1_theta(t),

x[2](t) = diff(R1_theta(t),t),

x[3](t) = R2_theta(t),

x[4](t) = diff(R2_theta(t),t)

Am I understanding correctly that the state equations say that the angular acceleration of both revolute joints is zero? This is clearly not the case when you simulate the model and view the plots for angular acceleration. Can someone explain to me what's going on? Model with worksheet attached.

## supress expression....

I have defined several expressions that keep coming up in my calculations.
Like :

Delta := -2*M*r+a^2+r^2;
Sigma := (a^2+r^2)^2-Delta*a^2*sin(theta)^2;

Is it possible to make maple recognize these objects whenever they appear in the result of a calculation?

## convert inside to string...

I have a set of edges like this

{{1:1,1:2},{1:1,2:1}.........}  like this several may be 300 like this or more

i want it to be converted to

{{"1:1","1:2"},{"1:1","2:1"},......}  like inside double qoutes only

kind help

## Can converting mathematical expressions to strings...

I have the following expression:

```q1:=2.800000000*10^(-30)*a+2.7800000000*10^(-29)*b+2.7800000000*10^(-31)+3.0*10^(-21)+2.*10^(-32)*c+3.*10^(-30)*d;
```

I saved it as a string, but the format seems to have changed.

`q2:=convert(q1,string)`

Can I output it as follows:

`"2.800000000*10^(-30)*a+2.7800000000*10^(-29)*b+2.7800000000*10^(-31)+3.0*10^(-21)+2.*10^(-32)*c+3.*10^(-30)*d"`

## Why does the precedure not solve?...

I am still learning Maple and so I would like to rely on you power users to help me out. I probably doing something which is not allowed or not using the best method. I would appreciate any advice. Thank you in advance    ProcQuestion.mw

## I want the numerical values of the partial derivat...

 > restart:
 >
 > N:=10
 (1)
 > PDE:=diff(u(y, t), t) = diff(u(y, t), y, y)
 (2)
 >
 > ICBC:= {u(y,0) = 0, u(0,t) = cos(t), u(N, t) = 0};
 (3)
 >
 > sol1:=pdsolve(PDE,ICBC,numeric,spacestep=0.025,timestep=0.00001):
 > u_at_1 := sol1:-value(u(y,t), t=0.1);
 > u_at_1(0);
 (4)

## LinearAlgebra conduct to an error...

Hi

The procedure below work well without using the package LinearAlgebra.

The package conduct to an error.

## How can the multiplication of two functions be con...

If i have p := 8*T(x, 7)*T(x, 2)+4*T(x, 5)*T(x, 1)+6*T(x, 3)*T(x, 3)+7*T(x, 1)*T(x, 4)

I want to convert the the multiplication functions like T(x, 7)*T(x, 2) into summation T(x, 7)+T(x, 2)