## Definition of Matrix after restart changed to _rta...

I'm having sone trouble with my matricies after running restart. When creating the matrice, everything is fine and they are defined as normal. But, if I run restart and try to erdefine them, they are defined as some form of

The only way I've been able to fix this besides restarting Maple is to either add or remove the colon after the matrix, depending on wether there was one. If ther was, when I remove it the matrix is defined normally and vice versa. I'm relatively new to Maple coming from Matlab and would like to start using it more, but this matrix thing is very frustrating. I've attached a copy of the maple file. Thanks

First definition, everything is normal:

## ball rolling on a surface...

I want to animate a ball rolling on the surface cos(abs(x)+abs(y)).  The ball mass m is 1kg, radius r is 0.1meters starts at (0.5,0.5,cos(abs(5)+abs(5))) meters using g=9.8.  If we say the initial velocity of the ball is pushed in some random direction.  How do I show the path of the ball and animate?

## A problem with matrix vector multiplication ...

Hi everibody

I work with Maple 2015 under OS-X El Capitan.

Using more than one matrix vector product (either M.V  or MatrixVectorMultiply(M,V)  ; M is a n by p matrix and V a column vector of size p) within the same block of commands generates an error.

Do other people have the same problem ?

SomethingGoesWrong.mw

PS : I know I can do this   X . <<1, 1, -1> | <-1, 2, 0>> but this doesn't explain the error I get

## How to replace a string by an expression in the ed...

I have many expressions in a worksheet like this:

latex(%, "equations.tex", append = true)

I should have defined a file name like this:

fname := "C:/home/MyStuff/Economics/MICRO NOTES/equations.tex"

And then replaced the first expression throughit the worksheet by:

latex(%, fname, append = true)

To acheive this I open the Find/Replace dialogue as in picture below:

This does not work. Instead of replacing with fname the result is "fname" .  Is there any way of doing what I want?

## how to print matrix like command in text file with...

interface(prettyprint=0):
interface(screenwidth=500):
with(LinearAlgebra):

expect

Matrix([[a1,a2,3],[5,6,7],[9,10,12]])

but

it print datatype = anything,storage = rectangular,order = Fortran_order,shape  and (2,1) etc

Matrix(3,3,{(2, 1) = 1, (3, 1) = 1, (3, 2) = 1},datatype = anything,storage = rectangular,order = Fortran_order,shape = []),

## what are the dynamical system which act on invaria...

what are the dynamical system which act on invariant manifold?

## how to search matrix ?...

Is it a complete set ? How to search matrix?

## "a problem was encountered while opening the workb...

Hey, this is not the I've had this encounter. I want to open this saved document but when I open it and Maple starts up it just hits me with "A problem was encountered while opening the workbook. Database is not opened". How can I get to open it properly and see my math notes?

How can this be prevented?

Any help?

Christian

## A simple evalf/Int crashes Maple...

`evalf(Int(x*(1-2*x^(3/10))^(10./3),x=0..1));  # Crashes Maple`

Note that:

int(x*(1-2*x^(3/10))^(10./3),x=0..1);
int(x*(1-2*x^(3/10))^(10/3),x=0..1);

are OK.

(Windows 7, Maple 2017.3, 64 bit)

## using of Glerkin method for solving two coupled eq...

Hi

I want to solve these equations in MAPLE, but something goes wrong.

 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 (1)
 >
 (2)
 >
 (3)
 >
 (4)
 >
 (5)
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >

11111111111111.mw

## Theta_double_dot term (some how) got equated to ze...

Hello everyone,

I am experiencing a strange result. The Theta_double_dot got equated to zero in line 1.7. Please see the red arrow.

(I am using the Physics package)

How can I solve this issue?

## CDF of a general discrete distribution...

x/2 seems completely wrong as a CDF. In other cases Maple correctly writes the CDF as a piecewise-constant function clipped to 0..1:

```with(Statistics):

dd := Distribution(ProbabilityFunction = 1/2, Support = 1 .. 2);

PDF(dd, x); # OK
(1/2)*Dirac(x-1)+(1/2)*Dirac(x-2)

CDF(dd, x);
(1/2)*x```

Also CDF seems to have issues with DiscreteValueMap specified using a list, a table or piecewise():

```dd := Distribution(ProbabilityFunction = 1/2, DiscreteValueMap = (n -> [1, 2][n]), Support = 1 .. 2);

PDF(dd, x); # OK
(1/2)*Dirac(x-1)+(1/2)*Dirac(x-2)

CDF(dd, x); # indeterminate
int((1/2)*Dirac(0)*Dirac(_t-1)+(1/2)*Dirac(0)*Dirac(_t-2), _t = -infinity .. x)```

## CDF of Binomial(2, 1/2) is wrong...

```with(Statistics):

CDF(Binomial(2, 1/2), x); # wrong
piecewise(x < 0, 0, 2 <= x, 1, 1)

CDF(Binomial(2, p), x); # also wrong
piecewise(x < 0, 0, 2 <= x, 1, p = 0, 1, p = 1, 0, 1)
```

Maple can actually generate PDFs for discrete distributions:

```bpdf := unapply(PDF(Binomial(2, 1/2), x), x);
x -> (1/4)*Dirac(x)+(1/2)*Dirac(x-1)+(1/4)*Dirac(x-2)

int(bpdf(t), t = -infinity .. x); # correct CDF
(1/4)*Heaviside(x)+(1/2)*Heaviside(x-1)+(1/4)*Heaviside(x-2)
```

But then functions of random variables do not seem to work :

```bdist := Distribution(PDF = bpdf, Support = -infinity .. infinity);

CDF(bdist, x); # OK
piecewise(x < 0, 0, x = 0, undefined, x < 1, 1/4, x = 1, undefined, x < 2, 3/4, x = 2,
undefined, 2 < x, 1)

CDF(add(RandomVariable(bdist), i = 1 .. 2), x); # indeterminate
int((1/16)*Dirac(_t)^2+(1/4)*Dirac(0)*Dirac(_t-1)+(3/8)*Dirac(0)*Dirac(_t-2)+(1/4)*Dirac(0)*
Dirac(_t-3)+(1/16)*Dirac(0)*Dirac(_t-4), _t = -infinity .. x)```

It's a bit disappointing that Maple generates PDFs in terms of the delta function but doesn't support them properly, because that could be an easy and natural way to define mixed distributions.

## How to formulate this eq. (system) with matrices a...

Apologies for possible double post, it seemingly locked up upon trying to post the first time.

So before I get as far as to ask for how to get a certain PDE system solved and plotted, I tried to fiddle a little bit around with linear algebra.

• First, the file SystemGoesWrong.mw . I have issues with declaring (same result if I remove the with(VectorCalculus)); as far as I can see, EQ0 and EQ00 should be the same, except that I have summed the vector in one of them. And the first that "works", is wrong: it returns a scaling of a vector. How come?
• But then I copy everything from the heading and down into a worksheet where I was already fighting some linear algebra things (can someone please explain?): SystemDeclaresBut.mw
Then EQ0 and EQ00 declare just fine! What is the issue?
• How do I get Maple to list the equations in "compact" form with vector-valued functions so that I can read and debug?  The actual PDE system I want to solve (numerically, of course), looks as follows: DE4Maple.pdf
That was also the reason why I tried to declare procedures (coordinate-wise maximum ...), but I guess that questions on how to extract a solution and plot it in a particular way will be its own posting after I have learned how to declare it.

The contents of the first file:

 >

# Since I do not have any idea of how to get vectors nicely, ...

... I replace U0, U1, U2 by u,v,w and use difftables U,V,W.  And y1, y2 replaced by y,z.

 >
 >
 (1)
 >
 >
 (2)
 >
 (3)

# The system

 >
 (4)
 >
 >
 >

... and of the second:

 >

Over to some linear algebra.

 >
 >
 >
 (1)
 >
 (2)
 >
 (3)
 >
 (4)
 >
 >
 >
 normsqbyDot := proc() local theArgs, arg, look, me, cf, term;    1   me := eval(procname,1);    2   theArgs := args;    3   look := tablelook(('procname')(theArgs),'[`/POS`(1,normsqbyDot,1), `/BIND`(1,1,`/y1`::VectorCalculus:-Vector), `/PATTERN`(`/y1`^2)]');    4   if look <> FAIL then    5     eval(look,`/FUNCNAME` = procname)        else    6     ('procname')(theArgs)        end if end proc
 >
 >
 normsqbyMatrixProduct := proc() local theArgs, arg, look, me, cf, term;    1   me := eval(procname,1);    2   theArgs := args;    3   look := tablelook(('procname')(theArgs),'[`/POS`(1,normsqbyMatrixProduct,1), `/BIND`(1,1,`/y1`::Matrix), `/PATTERN`(`/y1`^2)]');    4   if look <> FAIL then    5     eval(look,`/FUNCNAME` = procname)        else    6     ('procname')(theArgs)        end if end proc
 >
 >
 (5)
 >
 (6)
 >

# Since I do not have any idea of how to get vectors nicely, ...

... I replace U0, U1, U2 by u,v,w and use difftables U,V,W.  And y1, y2 replaced by y,z.

 >
 (7)
 >
 (8)
 >
 >
 (9)
 >
 (10)

# The system

 >
 (11)
 >
 (12)
 >