## Can someone solve this ?!?Crank-rocker...

I´ve got problems with solving this task! Please help me with the solutions. Maybe someone knows how it works. I solved it from 1-4 and don´t know 5-8

Thanks

Tim

The Crank - rocker consists of rocker 1, coupler 2 and rocker 4. It´s connected with swivel joints. The rack is fixed.
We look at the  point mass m in A and the torsion spring (with damper) in B0. The weight and the inert force because of the motion affect in A (vx,vy ax,ay). All other components are without mass, rotary inertia could also been disregarded.

## Polynomial equation with root only returns 1 solut...

I have the following equation: -(1/12)*x+1 = sqrt(x-6)+0.5

Right click -> Solve -> Obtain solutions for -> x, only returns 1 of the solutions (6.), but I know there's another solution as well (+/- root) from the quadric formula. I already set the _EnvAllSolutions=true variable, which did not help.

Why doesn't Maple return both solutions and how to get it to do that?

## why does this code terminate (kernel connection lo...

Hi

When I run the attached code (basically just a big loop that doesnt do anything) it terminates early (when i is about 4600).

On my computer I get the error message "kernel connection lost".

On other computers it just stops.

It seems to be quite memory intensive but I don't understand why it terminates. normally if i run a large loop it may take a long time but it will get there eventually. I dont understand why this terminates in the middle.

any ideas would be great!

thanks

## kernel connection lost...

I was running the BirthdayPi procedure that was somewhere here in mapleprimes.

I replaced the string evalf(.. _BigPi   with evalf(Pi, 1000000) and ran the procdure.  I hit the stop hand because it was taking too long then I ran it again with a different number.  shortly after it said kernel connection lost.

I just upgraded my memory from 1Gb to 2.5 Gb (ie I removed 2 of the 4  512 Mb chips and replaced those with 1 Gb chips).  Could that have something to do with it?

## How do i make the samples in a plot logaritmic?...

Hi all. I m using maple 11. I plot a figure with loglogplot the problem is that the number of points at the low part of the x axis is very low. I increase the number of points but because it is a logaritmic plot the step is still too large for the low numbers but too small for the high numbers. Any ideas how to solve this? Thank you in advance.

## int() and float input

by: Maple

This is one sort of Maple inconsistency that interests me. Why should the first example behave like evalf(Int(...)) and call `evalf/int` while the second example does not?

## Performance of an operation...

As we write a maple program to do whatever operation is, is it possible (in maple) to measure howmany operations per second was performed to achieve the desired result. Or in case of the iterative methods, how can we measure the speed by means of  iterations/second and/or the total time used to achieve the result. Is this kind of performance measurements possible in Maple?.

Thanks.

## timelimit

by: Maple

I was looking at the timelimit command in Maple, and wonder about whether it might be improved .

The help-page ?timelimit says that it suspends its checks while within builtin functions. It says that, inside builtins, the time limit is "ignored".

But Maple has a lot of builtins. And significant portions of the work may go on within them. Does this make the timelimit() function not useful, from a practical point of view?

What if timelimit were to make checks whenever garbage collection (gc) ocurred? That's a safe point, no? And gc can happen within some builtins? Or what if time checks were made at the same frequency that interrupt requests were checked? Those can happen within some builtins, at safe points.

Those were my thoughts, until I tried it. The command anames(builtin) shows that rtable() is a builtin. But I have found that timelimit will function within at least some rtable() calls.

## exploding a sparse float[8] Matrix

by: Maple

I was reminded of this by another thread.

It is faster to add in-place a large size storage=sparse float[8] Matrix into a new empty storage=rectangular float[8] Matrix than it is to convert it that way using the Matrix() or rtable() constructors.

Here's an example. First I'll do it with in-place Matrix addition. And then after that with a call to Matrix(). I measure the time to execute as well as the increase in bytes-allocated and bytes-used.

> with(LinearAlgebra):

> N := 500:
> A := RandomMatrix(N,'density'=0.1,
>                   'outputoptions'=['storage'='sparse',
>                                    'datatype'=float[8]]):

> st,ba,bu := time(),kernelopts(bytesalloc),kernelopts(bytesused):

> B := Matrix(N,'datatype'=float[8]):

> time()-st,kernelopts(bytesalloc)-ba,kernelopts(bytesused)-bu;
0.022, 2489912, 357907

## EdgeConnectivity in GraphTheory package...

I've got a weighted undirected graph with 166 nodes and 191 edges. When using EdgeConnectivity I get a strange message:

Error, (in GraphTheory:-EdgeConnectivity) invalid input: GraphTheory:-VertexConnectivity expects its 1st argument, G, to be of type GRAPHLN, but received GRAPHLN(undirected, unweighted, V, A, `GRAPHLN/table/5`, 0)

Who can help?

## Calculate the determinant of large size square mat...

I was running on Maple 11 to calculate the determinant of large size square matrices. The matrix is sparse with floating-point entries and the size is roughly 6000*6000. Because the matrix is sparse, I set "storage=sparse" in defining the matrix, so that there is no storage problem. But when I used the command dtn:=Determinant(A, method=float) to calculate the determinant, there were the following problems:

Error, (in Matrix) Maple was unable to allocate enough memory to complete this computation.  Please see ?alloc

## how does Maple solve nonlinear systems of equation...

I'm wondering if anyone can help me track down the various methods Maple uses to solve nonlinear systems of equations. In particular, I don't need an in-depth discussion, I'm mainly interested in finding a citation or two for a paper I'm working on. I'm aware of the approach using resultants and a discussion of it in Geddes, Czapor, and Labahn (1992). I'm also aware of Groebner bases. Are there any other methods Maple uses?

Best,

Shawn

## How do I edit an expression...

In Maple 11, the expression pallette has the following availble for click and insert:

{-x   x<a

{x   a<x

This above is combined in a single brace. I would like to add a third line to the single brace set, but I can not figure out how to do this. I tried using the piecewise command and converting it to 2D but it errors out:

piecewise(x < -1, x^3,-1 < x <1, x,x >= 1, 1-x)

Error, unexpected relational operator

Can one of you Maple Gurus' help?

Thanks!

## find detailed info on packages...

I'm trying to write some mapplets for my professor (in Maple 11/12). Most importantly I need a program for working with group theory.  I've looked at the help menus in maple on the group package and all of its commands, I also read all of the maple programming booklets.  Still I have no idea how to do simple things like create the group Z2 or S3 and Z+ Z2.  I anyone has any idea on where more information on these issues might be.

## What does assignment to f(x) mean in Maple?

by: Maple

In a recent post, a Maple user misunderstood what an assignment to f(x) meant. Since this is a common source of confusion, I thought it would be worthwhile to say more about this subject.

What is f(x)?
First, f(x) is a "function application" in Maple. It is f applied to the argument x. It is not really the same as what one thinks of as a function in mathematics. Consider a mathematical function such as sin(x+y). In Maple, this can be represented by an expression sin(x+y) or a procedure proc(x, y) sin(x+y) end proc (which can also be written in "operator form" as (x, y)->sin(x+y)). The expression or the procedure can then be assigned to a name such as g. The mathematical function is then represented by g in Maple, and not by g(x, y). Instead, if g is a procedure, then g(x, y) means "the procedure g called with arguments x and y". The "function" help page explains these concepts in more detail.

What is f(x):=x^2 in 1-d math?
Now let's move on to what f(x) := x^2 means. In 1-d math, this means, "Create a remember table entry for procedure f." This stores the expression x^2 so that when you enter f(x), that expression is automatically retrieved, and you avoid the expense of executing the body of the procedure . Similarly, if you enter f(1) := 5, then the value 5 is automatically returned when you enter f(1). Note that if you subsequently enter f(y), you won't get y^2 returned, unless f was already defined to return y^2 with input y. Remember tables are very useful and are heavily used by some Maple library procedures. However, the majority of Maple users do not need to worry about this feature and can do very useful things in Maple without ever knowing about it.

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