## 160 Reputation

12 years, 310 days

## Technical Support...

The installation process should not take that long.

I would recommend that you contact our Technical Support team to let them know that you are having problems.  A member of our Technical Support team should be able to help you resolve this problem.  The easiest way to get in touch with the Technical Support team is to send an email to support@maplesoft.com .

## My Guess...

From the error message, my guess is that you are doing something like this:

restart:

a:=Vector([1,2,3]);

a^2;

This will return the same error message that you are posting about.

If this is the case, the reason that this code doesn't work is because exponentiation of Vectors is not defined in Maple in this way.  Vector (and Matrix) multiplication is more complicated than scalar multiplication in that the size and orientation of the Vectors/Matrices is important.  To multiply combinations of vectors and matrices, the best thing to do would be to use the appropriate commands from the LinearAlgebra package or use the ' . ' operator for non-commutative or dot product multiplication.

## Unable to Reproduce...

I was unable to reproduce the issue that you have described.

I would suggest that you contact the Maplesoft Technical Support team by sending an email to support@maplesoft.com .  They may be able to help you solve the problem.  I would recommend letting them know exactly which Linux distribution you are using, and any other system information you think might be relevant.

## Convert to a Second Order DE...

Why not try converting the system to a second order system?

If the DE in question is x'(t)=f(t), we can differentiate both sides with respect to t giving x''(t)=f'(t).  Using the definition of the function f and the Fundamental Theorem of Calculus we know that f'(t)=exp(cos(t)).  We will also need an additional initial condition.  Knowing that x'(t)=f(t), we can substitute t=0 to obtain x'(0)=f(0) which implies that x'(0)=0.  Then we can create the DE plot using the following code:

DEplot({diff(x(t),t\$2)=exp(cos(t))},[x(t)],t=0..1,[[x(0)=1,D(x)(0)=0]]);

## Index Notation...

When used like you have done above, square brackets indicate a particular index in a data structure.  For example,  the code

N[0]:=1;

defines the 0th element of the data structure N to be 1.  Similarly, if b is already defined as 5 in Maple, the code

N[b]:=2;

defines the 5th element of the data structure N to be 2.  From your description, it seems like you are hoping to have variables named N0 and Nb that do not reference particular indices in a larger data structure N.  In 1D Math input mode, the easiest thing to do would be the following:

N0:=1;

b:=5;

Nb:=2;

This method keeps b and Nb completely indepedent of one another.

## Not Recommended...

Similar to what Axel Vogt has said, using the 'unprotect' command to override the protection on the name 'D' is (in general) not a good idea.  If you look on the Maple Help page for the 'unprotect' command, you will see under the heading 'Description' that it is not recommended that you use the 'unprotect' command to modify Maple system names.  It is possible, but it can lead to unexpected behaviour.  It seems that this is what you are experiencing here.

A better approach would be to simply name your Matrix D something else, like 'Diag' or 'Dee' and avoid the issue altogether.

## Plot is Not Shown On the Screen when Ass...

When you assign a plot command to a variable name (like you have done with the code f1:=plot(...)) Maples does not show the corresponding plot onscreen.  Instead it prints the 'PLOT(...)' output.  If you want to see the actual plot, you need to display it using the 'display' command.  The code

display(f1);

will show the plot f1 on the screen.  Additionally, if you create a second plot structure (say f2) and you want to display both f1 and f2 together, you would use the code

display(f1,f2);

## Nested For Loops...

Personally, I would accomplish this by using a nested for-loop.  (See the attached worksheet for an example.)

However, there are a few things worth noting about the problem you have supplied:

1) The Matrix M you have specified is actually 4 by 5, not 5 by 5.  (In the attached worksheet, I illustrate with a 4 by 5 Matrix.  The code would need to be modified slightly if you wanted to work with a 5 by 5 Matrix.)

2) If you were to try to calculate all of the entries of A by hand, you would note that there is at least one that would be undefined.  The (2,1) entry involves division by zero.  A(2,1)=M(2,1)/(JJ(2,2)-JJ(1,1)-2)=8/(5-3-2)=8/0=Uh-oh! If you were to use the code I have supplied in the attached worksheet, Maple would return an error when it got to calculating the (2,1) entry and quit right there.  You might want to consider adding an 'if' statement into the mix to handle these types of situations, similar to the second approach illustrated in the attached worksheet.

For_Loops.mw

## Infinite Solutions...

There is not a unique solution to the system of equations that you have provided.  The answer Maple returns is in terms of the "free variable" x4.  This means that x4 can take any value, and then using that value for x4 you can calculate x1, x2 and x3.  Together, x4 and the corresponding values for x1, x2, and x3 define one solution of the system.  Because x4 can be anything, this gives an infinite number of solutions.  Maple writes the solution in this way because it is a succinct way of writing all the solutions of the system.

## rtablesize...

In the worksheet interface, the default rtablesize value is 10, meaning that 10 is the largest-sized rtable (Array, Matrix or Vector) that will be displayed inline.  Any rtable with any dimension larger than rtablesize will display with a placeholder similar to the one pictured in your question.

You can change the rtablesize in your worksheet by entering the command 'interface(rtablesize=N):' where N is your desired maximum rtable dimension to be displayed inline.  For example, if I entered 'interface(rtablesize=15):' before entering a vector of length 11, the whole vector will be displayed inline.

## Using the 'dsolve' Command...

Solving this differential equation (both analytically and numerically) is quite easy using Maple's 'dsolve' command.  I have included a worksheet that illustrates how to use this command to obtain analytic and numerical solution.

DE_Solutions.mw

## How to Accomplish This...

Hello,

I have created a worksheet that illustrates how to use Maple to create your desired plot.

How_To_Create_Your_P.mw

Have a look through this worksheet and you should find that creating the plot is not too difficult at all!

## I have included a worksheet that I think...

I have included a worksheet that I think will be of assistance to you.  It shows you how to create a matrix in Maple containing the data that you want, and then shows how to export that data into an Excel worksheet.

Relevant_Workshee.mw

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