----------------------------------------------------------------------------------------------------------------------
Introduction

I have a matrix (named DC on the piece of code below) all the elements of which are complex numbers a+b*I with a and b floating point numbers.
I want to obtain the real part of DC.

Obviously, if you do something like :
DC := Matrix(2,2, [1.0+1.0*I, 1.0-1.0*I, -1.0+1.0*I, -1.0-1.0*I];
Re~(DC);

the result corresponds to the desired matrix

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Context

In fact this matrix DC comes from some computations  described in the piece of code below

# Purpose :
# Given N points in a plane (here  in [0,1]X[0,1]), compute the matrix DX of distances between these points
#
# Example : if Pi and Pj are two such points, DX[i,j]=DX[j,i] denotes the Euclidian distance between Pi and Pj
#
# As I did not be able to find any single function in MAPLE that would construct DX , I proceed that way :
#   1/ let X the (N,2) matrix that contains the coordinates of the N points
#   2/ I represent these  N points as N complex numbers (vector C)
#   3/ I construct the (N,N) matrix MC = <C | C …..| C>
#   4/ I put MC = C – Transpose(C) :
#   5/ I take the norm DX of each elements of DC : DX := abs~(DC)
#       At this point, DX should contain the desired distances
#       But, due to floating point arithmetics, each element of DX writes a+0.*I where a is some floating point number)
#   6/ Last stage : execute Re~(DX)
#

with(Statistics):
with(LinearAlgebra):

N := 4:
X := Matrix(N,2, convert(Sample(Uniform(0,1), 2*N), list)):  #just an example

C   := X[..,1] +~ X[..,2] *~I;
MC := Multiply(C, Vector[row](N, 1));
DC := MC - Transpose(MC);
DX := abs~(DC);
Re~(DX)


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 My observations : 

1/ Maple 2015, Windows XP, 64 bytes
Re~(DX) returns DX and does not remove the imaginary (0.*I) part
But  Matrix(N, N, Re~(convert(DC, list))) does (which is a satisfactory, even if not clever, stopgap)

Why (it is just a question to help me to understand correctly how MAPLE proceeds) Re~(DC) does not (seem) to work here ?


2/ Maple 2015.2, Mac OS X El Capitan
DX := abs~(DC) gives me this strange result :
If (for instance) DC[i, j] = -1 – 2*I, DX[i, j] = +1 + 2*I
According to the compatibility problems between Maple 2015.1 and “El Capitan” (fixed from February), could it remain a few other problems ?

Last but not lesat : Did I do any syntax error ?


 I look forward to your responses

I read in the net that the method used in pdsolve numeric is the theta method, my question: is it the most efficient with regard to rate of convergence of the numerical solution of the PDE?

If not then why is it used as the default method?

Thanks.

nullspace or reducedform or Eigenvectors still can not find eigenvector in terms of  mmm , how to find this?

mmm is a variable

 in eigenvector using nullspace and eigenvector using maple function  Eigenvectors ? 

I'm reading a string from a textbox, and I need to know where the line breaks are. Hint:They are not found by searching for \n.

hi.please see attached file below and help me.thanksode.mw

Download ode.mw

I am (again) trying to get Maple to do some parallel work; using the Threads package.

My actual problem involves a vector function with 6 elements, acting on 6-vectors. Each element of the output vector is calculated as a high-order polynomial of all 6 input elements. The whole thing is a map that I want to iterate. I plan to evaluate each of the 6 functions in a separate thread (the input vector of course is the same for all six) and then put the results together in a Vector, to be used as input for the next iteration.

Facing difficulty I finally wrote myself a little toy program to check out the basic mechanism. Here it is:

restart;
                "Maple Initialization loaded..."
with(Threads):
f:=x -> 1+x^2;
                                       2
                        f := x -> 1 + x
x:=0:
tt:=time[real]():

for i from 1 to 10 do
  id:=Create(f(x),y):
  Wait(id):
  x:=y:
  y:='y':
end do:

time[real]()-tt;
                             0.018
i;
                               11
So far so good; even the output (not shown) makes sense. BUT: as I increase the number of iterations in the for...do loop, the memory allocation goes up fast, and I hit a point at about 40 iterations where the whole process locks up and the program never ends, cannot even be stopped (at least for 100 iterations), forcing me to abort the whole thing. I have evidence that Maple allocates vast amounts of memory which finally chokes the whole thing (on a 16 GB-RAM machine).

Anyone have any idea what I am doing wrong? I realize the above example does not provide benefits; in the real example there will be 6 Creates and the loop will Wait for all of these to finish.

I'd really like to get this to work as each function can take quite some time and I do expect at least some speed-up from parallelizing this (even after overhead).

This is on Maple 2015 on Mac OS X 10.10.5 with 16 GB of RAM. I should mention that I set UseHardwareFlots:=true in my .mapleinit file.

Thanks,

M.D.

H2 := [a(t)*(diff(c(t), t))+b(t) = 100, a(t)*(diff(b(t), t))+c(t)*(diff(b(t), t)) = exp(t), a(t)*(diff(c(t), t))+a(t)*(diff(b(t), t))+b(t) = 90];
H1 := subs([diff(a(t),t)=a1,diff(b(t),t)=b1,diff(c(t),t)=c1], H2);
H := subs([a(t)=a0, b(t)=b0, c(t)=c0], H1);
ics := generate_ic(H, {a0=-2..2, b0=-2..2, c0=-2..2,a1 = -2 .. 2, b1 = -2 .. 2, c1 = -2 .. 2, t = 0, energy = 0}, 100);

Error, (in generate_ic) invalid input: `DEtools/generate_ic` expects its 1st argument, H, to be of type algebraic, but received [a0*c1+b0 = 100, a0*b1+c0*b1 = exp(t), a0*c1+a0*b1+b0 = 90]

Hi,

I would like to plot a cone where I can change the vertex angle directly. I would also to be able to change the size of the cone. I have tried:

cone([r*cos(phi)*sin(theta), r*sin(phi)*sin(theta), r*cos(theta)], phi = 0 .. 2*Pi, r = 0 .. 1, theta = (1/6)*Pi, coords = spherical)

but this gives me the following error:

Error, (in plot3d) unexpected options: [[r*cos(phi)*sin(theta), r*sin(phi)*sin(theta), r*cos(theta)], phi = 0 .. 2*Pi, r = 0 .. 1, theta = (1/6)*Pi]

Thanks!

with(DEtools):
phaseportrait([secret], [a(t), b(t), c(t)], t = -2 .. 2, [[a(0) = 1, b(0) = 0, c(0) = 2]], stepsize = 0.5e-1, scene = [c(t), a(t)], linecolour = sin((1/2)*t*Pi), method = classical[foreuler]);

Error, (in DEtools/phaseportrait) the ODE system does not contain derivatives of the unknown function a

Environment: Maple2015, MATLAB_R2014b(MacOSX10.8.5), 2015b(MacOSX10.11.4)

MapleToolbox2015.1MacInstaller.app was successfully completed (log tells us), but when MATLAB were booted, following error messages appeared and symbolic operations of maple failed. 

This would be closely related to maple installation on MATLAB as such errors never occur for clean install of MATLABs and looks independent on OSX versions. Now javaforosx.dmg in use by instruction of Maplesoft.  Something wrong is in Maple2015. Note maple-MATLAB link works normally.

Please provide us with direction of how to fix it hopefully by Maplesoft professionals.

(Quote of MATLAB command window display)

Exception in thread "Startup Class Loader" java.lang.UnsatisfiedLinkError: jogamp.common.os.MachineDescriptionRuntime.getPointerSizeInBytesImpl()I

at jogamp.common.os.MachineDescriptionRuntime.getPointerSizeInBytesImpl(Native Method)

at jogamp.common.os.MachineDescriptionRuntime.getRuntimeImpl(MachineDescriptionRuntime.java:138)

at jogamp.common.os.MachineDescriptionRuntime.getRuntime(MachineDescriptionRuntime.java:124)

at com.jogamp.common.os.Platform.<clinit>(Platform.java:228)

at javax.media.opengl.GLProfile.<clinit>(GLProfile.java:83)

at com.mathworks.hg.peer.JavaSceneServerPeer.initializeJOGL(JavaSceneServerPeer.java:114)

at com.mathworks.hg.peer.JavaSceneServerPeer.<clinit>(JavaSceneServerPeer.java:100)

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:190)

at com.mathworks.mde.desk.StartupClassLoader.loadClass(StartupClassLoader.java:258)

at com.mathworks.mde.desk.StartupClassLoader.access$900(StartupClassLoader.java:25)

at com.mathworks.mde.desk.StartupClassLoader$2.run(StartupClassLoader.java:244)

at java.lang.Thread.run(Thread.java:745)

>> maple();

error: maple (line 178)

Invalid MEX-file '/Applications/MATLAB_R2014b.app/toolbox/maple/maplemex.mexmaci64':

dlopen(/Applications/MATLAB_R2014b.app/toolbox/maple/maplemex.mexmaci64, 6): Symbol not found: ___sincos_stret

  Referenced from: /Library/Frameworks/Maple.framework/Versions/2015/bin.APPLE_UNIVERSAL_OSX/libhf.dylib

  Expected in: /usr/lib/libSystem.B.dylib

 in /Library/Frameworks/Maple.framework/Versions/2015/bin.APPLE_UNIVERSAL_OSX/libhf.dylib

>> syms x  y

error: sym (line 186)

Invalid MEX-file '/Applications/MATLAB_R2014b.app/toolbox/maple/maplemex.mexmaci64':

dlopen(/Applications/MATLAB_R2014b.app/toolbox/maple/maplemex.mexmaci64, 6): Symbol not found: ___sincos_stret

  Referenced from: /Library/Frameworks/Maple.framework/Versions/2015/bin.APPLE_UNIVERSAL_OSX/libhf.dylib

  Expected in: /usr/lib/libSystem.B.dylib

 in /Library/Frameworks/Maple.framework/Versions/2015/bin.APPLE_UNIVERSAL_OSX/libhf.dylib

 error: sym (line 56)

           assignin('caller',varargin{i},sym(varargin{i})); 

(Unquote)

Hello..  I want to know if there is anny command to show the matrix of linear system.  I recently entred a 64 equations and i solved it by command solve,  but i want to show the matrix of system..  So plz. Help 

I've got the following:

Integral_over_region.mw

M_Iwaniuk

hi .why matrix a dont create?

bot.mw

Download bot.mw

I have downloaded and trying to run the application "Traveling Salesman Problem" by Bruno Guerrieri: 

http://www.maplesoft.com/applications/view.aspx?SID=6873

However, the animations do not work properly. Instead of the animations, I get series of sets of plots. Each such set consists of four plots: one with a green edge, one with a blue edge, one with blue edges, and one with points (nodes).

I guess, it happens because of a new version of maple: the application was created in 2008 for Maple 12, and I use Maple 2015.

Could anybody, please, tell me what exactly should I change in the code so that it will work properly?

Any help will be very much appreciated.

Many thanks in advance!