## How to count elements?...

Assuming that I have the following row1 = a, b, c row2 = a, b, c row3 = b, c , a I would like to obtain for each column the frequencies: column1 a: 2, b: 1, c:0 column2 a:0, b:2, c: 1 column3 a:1, b:0, c:2 How could I do it with maple? Do I need to use some package? Thanks in advance, Jean

## Maple does not integrate when I use "for...do" loo...

Hi, I am trying to evaluate a number of N[i,j] variables and part of the process of finding them includes "Int" and afterwards "evalf". In case I calculate them manually as in (functions, variables and constants previously defined): G11 := diff(psi2, a[1], a[1]); dpsi2 := diff(psir2, a[1], a[1])+diff(psiz2, a[1], a[1]); Izr := -E*(Int(u*G11, [z = -infinity .. infinity, r = 0 .. infinity]))+Int(u*((j*g0+j^2/r^2+(1/4)*g0^2*r^2-2/rho)*G11+dpsi2), [z = -infinity .. infinity, r = 0 .. infinity]): Izr2 := evalf(Izr); N[1,1] := (a[1]*a[1])*Izr2; I obtain neat results for Izr2 and N[1,1] (i.e. the integration is done and results in a number).

## how maple inspires me -...

I updated my blog entry - for those who might be interested: me, blogging

## How to join multiple plots in 1 plot?...

Suppose I've plotted 3 functions:

plot(f(x),x=0..1);
plot(g(z),z=0..1);
plot(h(w),w=0..1);

Now I'd like to have these 3 plots following one after another (in a successive manner) in 1 plot like diagram. How can I perform such a task?

Another question:

How can I have a plot in reverse range? For example instead of plot(x^2,x=0..1), I'd like to have sth as plot(x^2,x=1..0), i.e. the horizontal range begins from 1 and ends to zero (also the vertical range is from (1)^2=1 to (0)^2=0).

## Time spend on calculating...

Why does Maple take (much) more time on calculating than Mathematica? For example, some time ago, I calculate this integration: int((sin(x)/x)^100,x=-infinity..infinity); although Maple is able to give the correct answer, but it takes about 5 minutes to achieve this answer. However, when I did the same thing in Mathematica, the time spent on calculating is less than one minute. Why is there such a notable distinction between the two computer algebra systems? PS: Versions of the two softwares that I use are Maple 11 and Mathematica 6.

## how to derivate?...

Hi everyone. Does anyone know how to derivate such function: piecewise(t and avoid in result: Float(undefined) in points where function is not continuous. You can see what I'm writing about in file trajectory I appended. The problem is that I have a big simulation of constrained robot and I need to derivate my equations which are not continuous and I cannot change it. Thanks for any help. Piotr P.S. I forgot to write I use MAPLE version 8

## Functions are not sticky...

Hello everyone, I have a problem with Maple 11, and I was wondering if anyone can provide insight. When I create a function, say: r := t-> [t^2, 2t, 3t^3]; And then somewhere further down my document I do... r(2); or perhaps.. plot3d(r(t), t=0..1); Etc... there are times where it appears that maple 'forgets' what my functions are and I'm forced to click on my initial function definition and press Enter again to 'remind' maple what 'r' is. I don't understand why this happens... if I say x=2 in a programming language, it stays =2 until I redefine it otherwise, but with maple my functions don't remain what I define them to be and I don't understand why my functions simply don't 'stick'???

## Question about the RowReduce command in LinearAlge...

Hey folks. I was wondering if there is anyone fairly well versed in the modular linear algebra package who can help me figure out how to solve a problem. I am doing some research about some coding theory, and I find myself needing to row reduce a matrix with entries from the integers modulo 2. I am using Maple 11 on a Mac, and have read the help file on the RowReduce command in the LinearAlgebra[Modular] package, which explains all of the parameters I need to include. I thought I understood the parameters, but I get an error each time I try to do use the command. The error I get states that the matrix is singular, which shouldn't be a problem since I am not trying to invert anything.

## Conversions, combines, collects, etc....

How do I get the ln's in ln(2*x-2*a)/a-ln(2*x)/a to combine? How do I get maple to convert exponentials into hyperbolics and back? In general, is there a good reference for collect, combine, convert, simplify, expand, factor and all similar functions? How to massage an expression into the form you want seems to be an enormous and/or hit or miss affair. Thanks.

## How Do I Do Conditional Probability with Maple?...

How Do I Do Conditional Probability with Maple? I use Maple 10 Retail Student. My word problem is "Should You Switch". What I want to know is how Do I use Maple to a) compute it and verify my work b) Use Maple for this. You are a contestant on a game show where a million dollars is hidden between on of three closed doors. You geuss door 1 BUT before opening that door the game show host opens door 2 and shows you that nothing is hidden there. He offers you the chance to switch your geuss to door 3. Should you switch? How do I use Maple to verify my work?

## Short question: Maple returns complex number solut...

Dear all! In the attached document X is a function in p and F. Solving X for F returns three possible solutions in p. When I put p=6 all three solutions contain complex numbers. However, when I put p=6 at the very top of the file, transforming X into a function of only F, Maple finds two possible solutions for F both without complex numbers (11.1 and 3371.9, whereas 11.1 is the "right one"). How come that Maple doesn't yield the same results when I define p=6 later in the file? I'd be very greatful for any suggestions and help! Best regards, Florian

## problem with y-axis labels in logplot...

Hello, I ran into some problems with the y-axis labeling and tickmarks, and would appreciate any help you could offer. Thanks! The y-axis plotted below has two 10^(-6) labels, and the tickmarks on the y-axis do not look correct either (more than 10 subtickmarks per order of magnitude!). -Dan > restart; >with(plots); > dBv[1] := 37.43; dBv[2] := 31.29; dBv[3] := 25.75; dBv[4] := 20.86; dBv[5] := 16.54; dBv[6] := 12.58; dBv[7] := 9.28; dBv[8] := 6.02; dBv[9] := 3.32; dBv[10] := 1.25; dBv[11] := -1.54; dBv[12] := -3.38; dBv[13] := -5.45; dBv[14] := -7.2; dBv[15] := -8.04; dBv[16] := -8.29; dBv[17] := -10.06; dBv[18] := -9.32; dBv[19] := -10.53; dBv[20] := -9.71;