I am struggling with the new LinearAlgebra package and I want a procedure for the vec operator (just stacking the colums of matrix r by c into a (r*c) by 1 columnvector. For only extracting two columns the following commands work well: A := Matrix(5, 5, symbol = a); Matrix([[Column(A, [1])], [Column(A, [1])]]); but there must be a simple procedure for doing this for a converting a large matrix into a column vector. Any help would be appreciated. kind regards, Harry Garst

I am converting a complex worksheet from linalg to LinearAlgebra, and
discovered what is to me a serious problem. With linalg, one could use
the basis(A,colspace) command to give a basis of the column space consisting of columns from the original matrix, guaranteed to be in the order in which they appear in the matrix. This is useful in extending a spanning set of a vector space to a basis of a larger space, and allows one to determine exactly which new vectors need to be added. However, the ColumnSpace(A) command in LinearAlgebra does something quite different. It gives a basis of the column space which does not preserve this order, and does not even use the original vectors.

One of the best features of MaplePrimes is that members can incorporate typeset 2-D mathematics into their posts—a huge advantage over text-only forums like Usenet, for example. MaplePrimes currently allows math input using either Maple syntax or MathML. There may be a straightforward way to support the input of 2-D math using TeX/LaTeX as well. This post suggests one possible way to add this new functionality to MaplePrimes.

Hello, all! I have a linear system of real numbers. I copied the example in the tutorial for using LinearSolve and converted my matrix to a float:
with(LinearAlgebra);
my_solve := proc(A::Matrix)
local sz, local_A, B, sol;
sz := Dimension(A);
local_A := Matrix(A, datatype=float);
B := Vector(1...sz[1], 1);
sol := LinearSolve(local_A, B);
end proc;
And when it solved, it got the wrong answer!! It would produce a solution that simply didn't work. When I removed the float conversion step, and just used my original matrix, it worked perfectly.
I would love to understand this better... is it because of rounding?

I've had considerable difficulty in integrating products of trig functions with Maple. It usually expands the trig functions into forms that just are a mess to deal with. So, I usually handle this by splitting an expression into two parts: a constant term that doesn't depend upon the integration variable and a dependent term. In the past, I've usually done this by hand but have now created a procedure to do this automatically.

February 09 2006
fawzi 8
I seems that CodeGeneration fortran uses internally lists that can get longer

than 100 elements converting complex procedures.

executing

"Fortran(long_procedure,defaulttype=float,optimize);"

I get the following error message

"Error, (in GetNameReplacementList) assigning to a long list, please use

Arrays"

9.5 handled this without problems.

I join a worksheet that (as very last command) shows the problem.

I reported already this problem to the technical support, but now I post it also here.

Fawzi

February 04 2006
rellik 8
I am trying to multiply a number in volts with a number in mV. the answer it gives me, though, is in [[V]]*[[mV]]. How do I make it convert the answer to [[V]] automatically?

Hi, I just bought Maple, and I'm really excited about it. I'm poking around in Maple, trying to get comfortable with it, by entering in a problem from my physics class. In this class, we use SI units, except that we express our angles in degrees.
I'm trying to find an easy way to have the trigonometric functions take degree arguments. I tried "with(Units); with(Units[Natural])", and entered an expression this way: "R_x = R*sin(15*deg)", and that almost worked. There were two problems, though:
1. R is apparently a unit in its own right...not *too* much of a problem (I can choose another letter), but annoying.

Lately I have been experimenting with

structured Gaussian elimination. This is a technique for reducing large sparse systems of linear equations to much smaller dense ones, which can then be solved using a modular method. Needless to say, I had to generate some large sparse linear systems.
I wanted the equations to be written as polynomials, because that is the natural sparse representation in Maple and it makes programming structured Gaussian elimination easier (you can use has and indets, for example). So I tried my favorite randpoly command. This was me trying to generate one linear equation:

Hi.
I have a transfer function like this one:
y:=(2.5)/((8*s^2+6*s+1)*s);
and I can make inverse Laplace transformation in time and plot it by:
y1:=invlaplace(y,s,t);
plot(y1,t=0..25);
I try it also with time delay in transfer function but it doesn`t work.
y:=(2.5*exp(-1.5*s))/((8*s^2+6*s+1)*s);
> y1:=invlaplace(y,s,t);
> plot(y1,t=0..25);
So i find a solution in differential equation and make an algorithm to convert transfer function to differential equation.
ode := 8*(diff(x(t), t, t))+6*(diff(x(t), t))+x(t) = 2.5*Heaviside(t-1.5);
ics := x(0) = 0, (D(x))(0) = 0;

dcasimir

asks for an efficient way to create a list of the first n primes, without invoking

**nextprime**, etc. An easy way to do this is to use a do loop to build up a sequence term by term. However, as Alec points out, this is not an efficient technique in Maple. It runs as O(n^2), where n is the number of items in the sequence. A way to avoid the inefficiency is to forego building a sequence and instead insert the items into a table. Then, after exiting the loop, convert the table to a list.

I'm trying to solve a partial differential equation with two boundary conditions below. The general solution contains arbitrary functions of the non-differentiated variable. These functions are solved for and assigned but do not appear in the final solution return. Can anybody help me with this?

**> restart;**

**> l:=lambda;**

I'm trying to solve a partial differential equation with two boundary conditions below. The general solution contains arbitrary functions of the non-differentiated variable. These functions are solved for and assigned but do not appear in the final solution return. Can anybody help me with this?

**> restart;**

**> l:=lambda;**

It would be really nice if Maple would include PDF support in the future. More and more people are producing content directly in PDF (with pdflatex for example) rather than PS. PS isn't even directly supported on the Mac directly; it is always converted to PDF before it is displayed. Most printers can process and print a PDF file directly. Does anybody else wish Maple could produce PDF?

I was able to create a stand-alone application from a M-file with MatLab 6.0 R12. Is it possible to do the same with Maple 9.5? I mean, can I take a Maple worksheet and convert it into a executable file which can be run on a PC that does not have Maple 9.5 installed? I would like to know since it is easier for me to create GUI applications with Maple 9.5 than with MatLab.