## matrix in singular...

Dear all

How to avoid in plot "matrix in singular" in my pde system

`> a1 := -2;                                     -2> b1 := 3;                                      3> c1 := -1;                                     -1> L := 15;                                     15> b := .25;                                    0.25> th := 1.5;                                     1.5> pde := diff(u(x, t), x, x, x, x, t...`

## Enter the solution of differential equations...

Hello Everybody.

Im new to Maple, so i have a couple of questions. In the last few days I have learned the basic of Maple, and now i would like to solve an differential equation.

The Math question is:

Enter the solution of differential equation:

http://www.studieportalen.dk/forums/ShowFile.aspx?id=1122047

In the link i have put in the informations from the math question.

## evaluation of dsovle(.) takes forever with NO erro...

I am trying to solve a system of nonlinear 36 differential-algebraic equations numerically in Maple. The last line of my code is the dsolve(.) command which is used to solve the DAE system. My problem is that it takes forever to evaluate the dsove(.) command. Maple does not give me any errors/warning, however, it keeps evaluating, and evaluating...nothing happens...

I have used stiff solvers as well hoping to make the process faster but that dowsn't work either.

## Newton Raphson and Romberg intergral....

The question is to use a program of modified newton raphson , incorporating the Romberg intergal procedure which i have already created, to create a new program which evaluates the integral f(alpha) = 1-10*int(tan(x)^alpha),from 0 to Pi/4.
The following needs to be incorporated in your program:

-Let ci be the approximation of alpha* on iterate i of your "modified newton raphson" method, then the program should run until:
|ci-c(i-1)|<10^(-6)

## Error, (in dsolve) found the following equations n...

Hello there,

` `

When I was trying to solve a differential equation with dsolve, I've got such a error report:

`> dsolve({Q(0) = F[Az], diff(Q(x), x) = q[2](x)});`
```Error, (in dsolve) found the following equations not depending on the unknowns
of the input system: {Q(0) = -(1/4)*l^2*q[0]-(1/4)*l^2*q[0]*exp(2)+F}```
` `

But if I only write:

`> dsolve(diff(Q(x),x)=q[2](x));`

then there is no problem.

## reset status bar...

Could i manually reset status bar (i.e. memory and time values)? restart; doesn't help.

## how to solve panel cutting problem in maple...

raw_panel_cuttin.doc

Given a large rectangular wooden panel, you want to cut specific quantities of smaller rectangles from it.

## Cardinality Constraint for QP Matrix form...

Ok, when I run the below code which maximize the risk adjuested portfolio returns
(long and short positions) in QP matrix form on empirical data I get very strange
allocations ie we go 100% or 100% short in almost all stocks except for a few
where the allocations are more appropriate like 0.2 etc.

# Maximize Risk Adjuested Return Matrix Form
# Minimize W'.Cov.W−W'.EV
# R=Return Matrix

EV := Vector([seq(ExpectedValue(Column(R, i)), i = 1 .. N)], datatype = float[8]):

## Packing Rectangles...

to find the maximum number of rectangles that can be orthogonally packed into a larger rectangle:

http://lagrange.ime.usp.br/~lobato/packing/run/index.php

1) can some maple code replicate this?

2) but what i really want is: what arrangement of a given a number of rectangles (of differing widths and lengths...

## Maple does not evaluate symbolic equations importe...

Hi everyone,

I am importing an .m file from MATLAB to Maple using the command: FromMFile(). The .m file uses a set of huge symbolic matrices with an output of a huge symbolic vector of 36 by 1. Each element of this vecot is supposed to form a second-order differential /or algebraic equation that I am planning to solve using the Maple DAE toolbox.

The problem I have is that while I execute the worksheet, Maple only evaluates the...

## Parameter exports of Grid[Launch] command....

If you look at Maple help on Grid[Launch] command there is an example of checking the prime numbers.

I do not understand why the timingData variable is empty after specifying it in exports parameter.

When I do not specify it in the exports parameter, the timingData variable has the same value as it had before calling Launch command.

I don't know why maple can't solve this PDE

> restart;

> PDE := 4.2000*10^6*(diff(u[1](x, t), t))-.445*(diff(u[1](x, t), x, x))+4200.*u[1](x, t)+464.82-20836.*x-15.832*t+4.0442*10^5*x^2+2953.7*x*t+0.14631e-1*t^2+9.6788*10^6*x^3-2.7139*10^5*x^2*t-.99786*x*t^2+0.15902e-4*t^3-1.0085*10^9*x^4-6.3082*10^6*x^3*t-1069.3*x^2*t^2-0.15006e-1*x*t^3-3.9073*10^(-8)*t^4+2.3478*10^10*x^5+2.5874*10^8*x^4*t+1.2265*10^5*x^3*t^2+2.9028*x^2*t^3+0.17521e-4*x*t^4+1.9407*10^(-11...

## How do I export to latex/pdf...

I'm using Maple 15 with Suse Linux 11.4

Export to latex produces a tex file which, when conveted by pdflatex contains all sorts of errors. The page margins are very large, parts are missing, the title appears alone on a page, lists of equations don't have line breaks so, for a long list you find just the central part going from edge to edge of the page.

I gave up using "Export to latex" on earlier versions. I had thought that Maple 15 might be better, but it seems worse.

## Problem with tensor product of Bras and Kets in th...

The Physics package appears broken for the tensor product of Bras and Kets.
It is not possible to describe new operators creatde by the tensorial
product of operators on two Hilbert spaces. ie H12 = H1 X H2

Am I missing something here.

Thank you for your help

## mserver.exe stopped working...

I have problem because mserver.exe stopped working

Yesterday that file was working very well.