# MaplePrimes Questions

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### How to order complex numbers?...

November 22 2015
1 6

Hello,

I would like to know how to order a sequence of number from smallest to largest. This is if I have both real and imaginary numbers. Any help would be rgeatly appreciated! Thank you in advance.

Kind regards,

Gamiba Man

### Why does Maple produce "I"?...

November 22 2015
0 1

I'm solving a problem described in this topic.

It's sufficient for me to obtain N variable via this manual procedure: file4.mw

However when I want to quantify an expression (f) for any N (e.g. N=40), Maple shows a value with some I variable:

What does it mean?

### Flux through a cone...

November 22 2015
1 2

I'm trying to calculate flux through a cone but gets the following:

Flux(VectorField(`<,>`(x, y, z), cartesian[x, y, z]), Surface(`<,>`(x,y,z), x^2+y^2<=2*a,z = 2*a-sqrt(x^2+y^2)))
Error, (in VectorCalculus:-Flux) error with surface input

### How to plot HeunTPrime in Maple?...

November 22 2015
0 8

HeunTPrime.mw

Hi all,

I hope the best for every of you...

I wonder how it can be possible to plot this function (HeunTPrime) in Maple18???

Thanks a lot

### Problems plotting function...

November 21 2015
0 2

Hi, i need to plot n(celle) versus vavg, is it possible? i have tried a lot of different things without luck.

navg is in the range between 0-10

ts is between 0-100

Hope one of you can help me!

Thanks

### Problem with gamma as variable...

November 21 2015
1 4

 (1)

 (2)

 (3)

 (4)

 (5)

 (6)

how can i solve this problem?

### How to use Greek alphabet in Maple?...

November 21 2015
0 4

hello

I have recently install Maple17 on my computer (Windows10) and I need to use some Greece alphabet such as ß but I look everywhere in maple's icon and I just could find capital Greece alphabet.

does anybody know how can I find those?

### Error in procedure...

November 21 2015
0 1

Hello,

I'm having an issue with this and I can't seem to fix it. Any help is greatly appreciated! Thank you in advance!!! For some reason mapleprimes won't let me upload the worksheet so I have pasted it below this message.

Kind regards.

Gambia Man

with(LinearAlgebra); UseHardwareFloats; with(plots); interface(rtablesize = infinity); with(Statistics);
L := 4; U := 1;
V := proc (x, y) options operator, arrow; piecewise((1/4)*L <= x and x <= (1/2)*L and (1/4)*L <= y and y <= (1/2)*L, U) end proc;
plot3d(V(x, y), x = 0 .. L, y = 0 .. L);

Vij := proc (ni, mi, nj, mj) local Xi, Xj; option remember; global U, L; Xi := 2*sin(ni*evalf(Pi)*x/L)*sin(mi*evalf(Pi)*y/L)/L; Xj := 2*sin(nj*evalf(Pi)*x/L)*sin(mj*evalf(Pi)*y/L)/L; return U*(int(int(Xi*Xj, x = (1/4)*L .. (1/2)*L), y = (1/4)*L .. (1/2)*L)) end proc;
HamilMat := proc (K::integer) local ni, mi, nj, mj, N, Hamil, Eigenvec, i, j, res; option remember; global Vij, U, L; N := K^2; ni := Vector(N); mi := Vector(N); nj := Vector[row](N); mj := Vector[row](N); for i to N do for j to K do res := (i+K-j)/K; if type(res, integer) = true then ni[i] := j; nj[i] := j; mi[i] := res; mj[i] := res end if end do end do; Hamil := Matrix(N, shape = symmetric); for i to N do for j from i to N do if i <> j then Hamil(i, j) := Vij(ni[i], mi[i], nj[j], mj[j]) elif i = j then Hamil(i, j) := Vij(ni[i], mi[i], nj[j], mj[j])+(1/2)*(ni[i]^2+mi[i]^2)*Pi^2/L^2 end if end do end do; Eigenvec := Eigenvectors(Hamil, output = ['values', 'vectors']), Hamil end proc;
SigFigEi := proc (Location::integer, SigFig::integer, VecSize::integer) local values, Eig, i; global HamilMat, OptK; Eig := Vector(VecSize); for i from 2 to VecSize do Eig[i] := HamilMat(i)[1][Location]; if evalf(Eig(i), SigFig+1) = evalf(Eig(i-1), SigFig+1) then OptK := i; break end if end do; values := evalf(Eig[i], SigFig); return values, OptK end proc;
BasisFunc := proc (location) local ni, mi, func, i, j, p, N, res, BasisSol; global HamilMat, L, OptK; p := evalf(Pi); N := OptK^2; ni := Vector(N); mi := Vector(N); for i to N do for j to OptK do res := (i+OptK-j)/OptK; if type(res, integer) = true then ni[i] := j; mi[i] := res end if end do end do; func := Vector(N); for i to N do func[i] := HamilMat(OptK)[2][i][location]*sin(ni[i]*p*x/L)*sin(mi[i]*p*y/L) end do; BasisSol := unapply(add(func[i], i = 1 .. N), x, y); return plot3d(BasisSol(x, y), x = 0 .. L, y = 0 .. L), func end proc;
BasisFunc(1);
Error, (in Vector) dimension parameter is required for this form of initializer

### Collecting coeffients in a huge sum...

November 21 2015
1 4

Note added: Issue resolved, see my comment below.

I have a sum of several thousands addends each of which is the product of a c-number times a product of 6 Grassmann-odd degrees of freedom, the latter of which does each belong to a set of 24 Grassmannians. The specific numbers are not that important, though.

This sum should equal zero. So I would like to add all c-numbers multiplying the same product of six Grassmannians, taking proper care of anticommutativity, of course. The sum would then be zero if all these sums of c-numbers are zero. Unfortunately, using Physics:-Coefficients is far too slow; actually, it has never succeeded in even completing the calculation.

Therefore, I have tried to loop through all the addends, splitting each one of them using selectremove(), and then adding the c-numbers in an Array (properly indexed), or in a table (associatively indexed, of course). Consistently, by converting the Array and table to two sets, the two methods result in the same set of equations. But solving these equations yields a result that is not stable: it varies from session to session.

I am baffled. Can anyone give me a hint to a safe and reasonably quick method for extracting these c-number-valued equations?, for there has to be something wrong with what I do.

### Everything is too small...

November 21 2015
0 3

Hi

Hope somebody can help me! I installed Maple on my computer, but everything is very small , for example the bar in the top with all the small icons. It is the same thing when I make plots. The values on the axes are very small. How can I change this?

I have taken a photo of the problem, don't know if it helps.

### Problem in combinatorial geometry...

November 21 2015
0 22

Let four straight lines in general position be given. Their complement consists of  11 domains. One can choose four (PS. different) points belonging to the pieces s.t. exactly two points lie astride everyone of these lines. Here is an example.

How many are such configurations (If the points belong to the same pieces, two configurations are equivalent. PS. I.e. one may move points in the  pieces.)?
How to determine it with Maple? Robert Israel used GraphTheory, having answered that.

### Change legend location to any point...

November 21 2015
0 1

i need to plot tow functions but the legend not in top, bottom, left or right

### How to find the w and phi?...

November 20 2015
1 5

1.

assume there are 3 real number or floating number a, b, c

how to find the w and phi in

a = sin(w*t1 + phi)

b = sin(w*t2 + phi)

c = sin(w*t3 + phi)

where w and phi are the same in above 3 equations, only different in t1, t2, t3

2.

same as above , how to find w, apha and beta in below if there are a, b, c

a = alpha*cos(w*t) + beta*sin(w*t)

b = alpha*cos(w*t) + beta*sin(w*t)

c = alpha*cos(w*t) + beta*sin(w*t)

### How to find linear combination? ...

November 20 2015
0 1

assume there is vector a,b,c and d which are real number or floating number

how to express a in linear combination of b ,c and d

in another words, how to find coefficient m1, m2, m3

in a = m1*b + m2*c + m3*d

can LinearSolve do this?

### Passing Functions to a Matrix ...

November 20 2015
1 3

In Maple 18, I'm trying to define a matrix consisting of the output of the diff function from Physics, but it seems to return an empty matrix for some reason.

First, the setup:

with(Physics);
(D(x))(t) := x(t)^2+y(t)^2;
(D(y))(t) := x(t)^2-y(t)^2;

Then if I try to input the output of e.g. diff(x'(t),x(t)) directly into a matrix structure, it outputs an empty space for that entry.

I can work around it setting the output of diff into variables first, and then using those in my matrix structure, but that's a bit annoying.

See attached image for input/output

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