## Backup file not able to open...

Hi!

I've been working on a file in Maple, and saved it yesterday - but now I am not able to open it, as it is corrupted. I have been able to find the back up file, HOWEVER I am not able to load half of the file as Maple comes up with a "there was a problem loading your file....". Is there anything I can do to repair the back up file?

Any help is greatly appreciated!

## Multiple Nyquist Plot...

Is it possible to graph multiple Niquist plots using DynamicSystems:-NiquistPlot() ? All my attemps have failed.

Thanks.

## How I can remove Root of in solving process...

How I can ontain results without Rootof !!

Thanks

help.mw

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## Classification of satellite image ...

Hi,

Can i use Maple to do satellite image classification . by implement the satellite image so the software will do the math processing ?

## how to plot tsai wu failure envlope in maple?...

Hi,

I want to plot the Tsai Wu failure envelope for a given
composite. The Tsai Wu failure criterion (for a pure biaxial
state of stress) is given by:

F1*x+F2*y+F11*x^2+F22*y^2+F12*x*y=1

## unevaluated/inert Matrix-Vector product?...

Can Maple carry around an unevaluated/inert  Matrix-Vector product(A matrix product without executing the matrix multiplication)? See Maple sheet.

inert_matrix_products.mw

Can Maple carry around an unevaluated/inert explicit Matrix-Vector product?

Define a matrix K and vector U as:

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I can take their product using MatrixVectorMultiply( ) I get,

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however output I am really looking for is

In the later case,  is still a product however the actual matrix multiplication is not carried out. Sure, eventually I will want to evaluate the matrix-vector product but sometimes when setting up a problem I want to look at the explicit matrix equation before any explicit matrix multiplication is carried out.

Here I show some ideas that don't work but may give a sense of what I am going for. I am essentially trying to mute the computation of the product while keeping the elements of the product together for further substitutions elsewhere. This there a standardized way to complish this? Or do I have to write my own procedure for something like this?

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## Piecewise with DotProduct...

I'm having trouble performing a direct operation, involving DotProduct, in the piecewise function. Attached is a document. I appreciate any contribution.

Regards,

Oliveira

Example2.mw

## Automatic simplifications not working?...

Hi,

I am new to Maple and I couldn't really find anything about this problem. Why doesn't Maple automatically simplify the last expression in the following? (see for example the first and last terms, as well as other terms)

r2r2 := %;

couldnt insert "r2r2" properly...

## What is the meaning of this error in pdsolve comma...

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Help me in finding the solution of system eq1 and eq2.

## What is the resolution of Plot3D images...

Hope the resolution of the images which come via Plot3d and plot commands are atleast 300 dpi

If not how to make them

## Solving PDE with imaginary unit ?...

I want solve PDE equation with imaginary unit ,but Maple give me an Error:

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If I delete Imaginary unit from equation Maple give me a solution.

Thanks .

## How can one determine whether a given set of edges...

I previously asked the following question, and a primes member dharr  provided a perfect answer. The question I asked today is slightly different.

An edge cut of a graph G induced by a partition of G's vertices into sets X and Y is the set of all edges with one endpoint in X and another endpoint in Y.

An edge separator is a set of edges whose removal will increase the number of connected components in the graph.

Note that these are two distinct concepts and cannot be considered equivalent.

An edge separator is not necessarily an edge cut. For example, for the complete bipartite graph K3,3, a set of any seven edges of K3,3 is an edge separator, but a set of any seven edges of K3,3 is not an edge cut.

It is easy to determine whether a set of edges is an edge separator.

```with(GraphTheory):
with(combinat):
G:=CompleteGraph(3,3);
edge:=choose(Edges(G), 7):
seq(nops(ConnectedComponents(DeleteEdge(G,s,inplace= false))),s in edge)
```

4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

For another exmaple,

In  the left  figure,  the brown edges highlighted represent an edge-separating set, but it is not an edge cut. The set of brown edges on the right is an edge cut.

But how to determine if a set of edges is an edge cut of a graph? I don't have a good idea yet, but I have a rough idea which is to color the set of vertex-ends of edges under consideration and then see if a partition as defined by the edge cut can be found.

## How to produce this solution in Maple. Result from...

I am converting some code from Mathematica. In it there is this solution

```eqs={2c2+c0==1,6c3+2c1==2,3c2+12c4==1};
FindInstance[eqs,{c0,c1,c2,c3,c4}]```

Which gives

`{{c0 -> 0, c1 -> 0, c2 -> 1/2, c3 -> 1/3, c4 -> -(1/24)}}`

Maple's solve gives

```eqs := [2*c2 + c0 = 1, 6*c3 + 2*c1 = 2, 3*c2 + 12*c4 = 1];
sol:=solve(eqs, {c0, c1, c2, c3, c4})```

Gives

`sol := {c0 = 1/3 + 8*c4, c1 = -3*c3 + 1, c2 = 1/3 - 4*c4, c3 = c3, c4 = c4}`

I know that both are correct solutions. But I'am asking if there is a command or an option I overlooked that will generate the same result as the above from FindInstance, which will make it easier for me.

May be there is another solver package or command I could try?

I am not sure what algorithm FindInstance uses. The documentation page does not say.

## Meaning of SymmetryGroup in the Logic package...

I am trying to understand the SymmetryGroup returned in the Logic Package. The help page says "The group is a permutation group; its elements are those permutations which preserve the Boolean structure of expr." [my bold], but later the definition is given as "A symmetry of a Boolean expression expr is a mapping f of each variable to some other variable or negated variable, such that the image of expr after applying f to each of its variables is a Boolean formula which is equivalent to expr." Is logically equivalent meant here, or something else? The help page examples don't answer this question.

The following example shows that a group permutation does not lead to a logically equivalent statement as I was expecting - is this a bug, or am I expecting too much here?

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Exchanging x[1] with x[2], and (not x[1]) with (not x[2]) leads to a logically equivalent expression, so this is indeed a symmetry.

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Exchanging x[3] with (not x[3]) leads to an expression that perhaps has the same form but is not equivalent

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