## Propagation of (anti-)symmetries

I am working on a new package, called "Spacetime", which I intend should be able to treat any physical field, either tensorial (integer-valued spin, like the photon) or spinorial (half-integer valued spin, like the electron) on any curved Riemannian manifold (gravity, according to Einstein). Anyway, for the Maple specific part: I have decided to implement these general fields as multi-dimensional Arrays, analogous to the older package "Gravitation", which "Spacetime" is intended to replace. They may have some symmetries and/or antisymmetries among their various indices. That part, that is, setting up the appropiate indexing functions, even in the general case, I have solved.

## Some problems with Maple 11.01

by:
I submitted, to Maplesoft, a document that describes several bugs in Maple 11.01. A copy of the document is available here: http://www.informath.org/maple/Problems-1101.mw (Note: the document is about 900 kB, which is currently too large for MaplePrimes upload.)

## Maple 11 solve command does not seem to be able...

by:
The following system of equations can be solved by Maple 9.5 and Maple 10, but either takes a long time in Maple 11 or else simply won't solve. Is anyone else experiencing problems with the solve command? Earlier I noticed that Maple 11 was returning duplicates in solutions, but this is more serious. We tried this system on Maple 9.5 and Maple 10, and it solves easily, but on two computers with Maple 11, in classic worksheet mode, minutes went by with no solution. {2*a[2,6]*a[2,9]-2*a[2,8]*a[2,9], 2*a[1,5]*a[3,1]+2*a[1,7]*a[3,1], 2*a[2,6]*a[3,4]-2*a[2,8]*a[3,4], 2*a[1,5]*a[2,1]+2*a[1,7]*

## Bug in Maple 11 densityplot?

by:
Under Maple 10, the command ``` densityplot(10-x-y, x = 0 .. 3, y = -x .. x, scaling = constrained, colorstyle = HUE, style = patchnogrid) ```

## The Maplesoft Great Application Contest

by:
Got a Maple application that will knock our socks off? Something with cool images, elegant math, or just a great introduction to using Differential Equations? We want to see it! Maplesoft is running a contest to find the best new Maple applications out there. To enter, simply contribute your document on the Maple Application Center, including the line “The Maplesoft Great Application Contest” in the Comments box. (However, all submissions to the Maple Application Center will automatically be considered.) Submissions must be received by January 15, 2008. One grand prize will be awarded, consisting of one of:
Apple iPod Nano Canon Powershot digital camera A460 4.5” (114mm) reflector telescope Deluxe wooden chess set
Runner-up winners will receive their choice of:
Maplesoft laser pointer pen Maplesoft mug Maplesoft hat
Submission Guidelines: Award-winning applications will:
Be created in Maple 11 Make use of the new Maple “Document Interface” including 2-D math input Be well-formatted and laid out; for instance, you could use tables to format your document
They may additionally have some of the following characteristics:
Use Embedded Components Use the “Point-and-Click” paradigm
Make sure your application includes instructions. Some things to consider while writing the instructions are whether the document can be modified and re-executed, if a user will interact with the document using Embedded Components, and whether a user needs to follow instructions to use interactive tools. The following Maple documents are good examples of appropriate applications:

## JavaViewLib with Maple 11

by: Maple
Hi, is the JavaViewLib package 3.22 running with Maple 11? After: ``` libname := "/home_zam/plch/maple/JavaViewLib", libname: with(JavaViewLib): ``` (this works fine in Maple 10) I received: `Warning, system/ssystem calls have been disabled in the options dialog.` Any suggestions? With best regards. Roman

## Sparse Polynomial Arithmetic

by:
I am pleased (and terrified) to announce the first public release of a Maple library for high performance sparse polynomial arithmetic. This C library and Maple interface is under development at Simon Fraser University in Vancouver, Canada. We are releasing this interim version so that Maple enthusiasts and researchers can try it. Maple 11 is required.

## Linear independence of matrices

I have twelve 4x4 matrices with specific complex-valued entries. I would like to know if they are linear independent over the reals. Is there some feature of Maple that enables me to do that easily? I've tried adding together all the matrices, each separately multiplied by an unspecified algebraic number, and then to use solve(). But I don't trust the result, partly because it becomes rather tedious, partly because the package RealDomain, with which I've no experience, has to be invoked in order to avoid producing a false solution of linear dependence over the complex numbers. I've also tried defining a 12x12 matrix consisting of bilinear traces of the matrices, analogous to the Cartan matrix in Lie algebra theory, and then taking the determinant to test for degeneracy.

## Width and depth

Why is something like
```V := Vector(2,(i) -> Matrix(3,3));
```
not equivalent to
```V := Vector([Matrix(3,3),Matrix(3,3)]);
```
which raises the error "Error, (in Vector) initializer list contains elements of width > 1 and depth > 1", but instead equivalent to
```V := Vector([[Matrix(3,3)],[Matrix(3,3)]]);
```
Why the need for extra pairs of [...]?

## dummy real function f of real variables r and z

Hi everyone, I m a beginner with maple, so please, be patient with me! I m trying to use some complex algebra in maple. In particular, I want to define a function f(r,z) and I want to impose it to be REAL. So I thought, let's first impose the variables to be real(I'm using Maple 10, so I write everything as if I was in a document, ok?): assume(r,real) assume(z,real) after I have done this, I define the function, using the appropriate f(x,y) button in the toolbar: F:=f(r,z) and I impose it to be real: assume(F, real) but for some reason this does not work. Anyone knows why? The reason why I need to impose the function to be real is that F will be later multiplied by exp(Iz) to form a complex number.

## Now you see it, now you don't

Yesterday I was astonished to discover that the information in the fields "About Me" and "Contact and Profile Information" had vanished, or, more precisely, had been rolled back to some older version. Naturally, since then I've tried to remedy that by reentering the newest version (remembering, of course, to click the submit button), but to no avail, or, more precisely: it works fine as long as I do not log out; after logging in again the information have gone to the 'eternal cyberspace fields of lost bits and bytes'. Have anyone else experienced the same odd behaviour? I should say that I have also tried to hit the refresh button (F5) of my browser, and tried erasing all temporary- and offline files, but also to no avail.

## Plots of twisted ribbons

Maple

In order to get better acquainted with the plotting facilities of Maple I thought I would try to plot the Möbius strip. In the proces I generalized the task so that I would be able to plot a ribbon twisted an arbitrary number of times. From these efforts the following code resulted:

```with(plots):
ribbonVector := (phi) -> Vector([-sin(phi)*cos(phi),-sin(phi)*sin(phi),cos(phi)]):
p := (twist,theTitle,theOrientation) -> plot3d(
title=theTitle,orientation=theOrientation,grid=[100,10],scaling=constrained
):
```

Below follow two examples: 1. Ribbon with 1/2 twist: The Möbius strip:

```display(p(1/2,"Ribbon with 1/2 twist: The Möbius strip",[200,70]));
```

2. Ribbon with 1/1 twist:

```display(p(1/1,"Ribbon with 1/1 twist",[40,60]));
```

## MAple 10 and Problem Solving

by:
As a math phobic, I took a class this semester at UConn Math102Q. The instructor is pretty good but now at mid-semester there are a lot of "do more problems" answers. I hoped at the beginning this would help with my math phobia. The course is fairly new and uses the PSSSP model and the book is written by DeFranco and Vinsonhaler.

## Navigating through very long threads

Hi guys, when browsing very long discussion threads, it would be nice to have a button or link that quickly moves to the top of the page. Currently I have to use the vertical scroll bar or mouse wheel. Sorry if this has been suggested before (I didn't follow this forum closely). Thank you!

## ALGERBRA !!!!

by:
SOME ONE PLEASE HELP ME WITH MY DAMM ALGERBRA I DONT GET IT WELL YEA SOME ONE THNKS .
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