## MaplePrimes Questions

Hello, suppose you have the following function which gives 1 if both its arguments are even: G := (i,j) -> if is(i,even) and is(j,even) then 1; else 0; end if; Then what is the difference between these two statements: sum( sum( G(i,j), i=0..5 ), j=0..5 ); add( add( G(i,j), i=0..5 ), j=0..5 ); The first one gives 0 and no sum is actually computed (you can see this by adding print(i) and print(j) statements in the body of G). The second one gives the correct result, namely 9. How come i is not replaced in sum? -- Thanks for any reply, Franky.

## plotting multiple 3d data sets on a single plot...

How do i plot a bunch of 3D data sets. If it were just one set i could use pointplot3d i suppose. with(plots): > l1 := [[1,2,2],[3,4,2],[1,5,6],[7,8,9]]; > l2 := [[1,2,2.5],[3,4,2],[1,5,6],[7,8,9]]; > plots[pointplot3d]([l1,l2], axes=boxed, labels=[x, y, z], > connect=true); #DOESNT WORK More exactly i want to plot the data sets (11 rows each) pasted below. 1.000000000000 1.000000000000 .571428571400 2.000000000000 1.000000000000 .139941691000 3.000000000000 1.000000000000 .068542869040 4.000000000000 1.000000000000 .041965021860 5.000000000000 1.000000000000 .028776014990

## Embedding Information...

I was wondering if anyone was familiar with an easy way to embed or hide information into a Maple worksheet (Classic worksheet or Maple 9/9.5 standard worksheet, NOT a Maple 10 standard worksheet)? I want to be able to be able to have something equivalent to a checksum. We are producing Maple worksheets as homework for students, and I want to have something that the sudent cannot easily change to make sure that he or she is not submitting a friend's homework.

## Very good books of Maple.. which ones?...

Hello, I want to learn how to program with Maple..Could someone - please- suggest a couple of very goods (..if they exist) for that purpose?. Regards, Jean Jacques.

## Graphing differential equation...

Hey guys, I'm having a bit of trouble graphing the following: f'''(x) + f(x)*f''(x) = 0 where f(0)=f'(0)=0 and f'(infinity)=1 My specific problem is that I can't set f'(0)=0 and f'(infinity)=1 thanks, Rebecca

I am trying to solve (numerically) the following system of differential equations using dsolve (Maple 9): DGLS:=seq(seq(diff(B[i,k](t),t)=add(add(W(j,l,i,k)*B[j,l](t)-W(i,k,j,l)*B[i,k](t),l=1..N),j=1..N),k=1..N),i=1..N); The problem is posed by the coefficients W(i,k,j,l). I want to make the W(i,j,k,l) dependent on the unknown functions B[i,k](t). For that purpose I wrote a Maple program W := proc(i::integer, k::integer, j::integer, l::integer) which calculates a "transition probability" Wtrans. If Wtrans does not depend on the B[j,l] (e.g. Wtrans:=1/N^2;), everything works nice. However, if I try to use the B[i,k] somehow (e.g. if NKrit_jl > B[j,l] then Wtrans := 0.5 fi;), then error messages from the procedure W result like "Error, invalid terms in product".

## Extracting an integer coefficient from a term...

What is an efficient, robust, way to extract an integer coefficient from a single term? My first thought was using lcoeff, however, it doesn't work if the term contains constants (say Pi) or floats. Currently I'm using patmatch,
```icoeff := proc(t)
local k,x,kx;
return `if`(patmatch(t, k::'nonunit'(integer)*x::anything,kx)
,eval(k,kx)
,1);
end proc:
map(icoeff, [0, 1, -3.0, -3, -0.,  3.0*Pi, 4*Pi, -12/5*I]);
[0, 1, 1, -3, 1, 1, 4, 1]
```

## Can anyone tell me the difference of maple used in...

One of my friends told me that Maple used in Linux(SUSE) is unstable,^_^，what he said may be wrong.I need more information about these,Anyone has even used maple in Linux(SUSE)? Can you tell me the difference of maple using in between Linux(SUSE) and Linux(RedHat)? I want to install maple V10 in SuperComputer Center for parallel computing.

## ¿Where do I get Maplet Builder for Maple 9.5?...

Hi. I have done some reseach and I can't seem to find where to download the Maplet Builder for Maple 9.5. It was suppose I could download it from Maple Primes, but I don't find the appropriate link.

## How to analyze (local) convexity with Maple?...

Hi dear Maple experts, I have a function f:= sin(x^2+y^2) and 1. I want to analize the convexity/concavity at a specific point (x,y) = (1/100,1/100) 2. It would be possible to check the convexity/concavity for all (relevant) points on the region x=-3..3, y=-3..3 ? (I suppose that is needed to discretize this region). 3. It would be possible to show a graphic (in R2) with colours (say, red for convex, blue for concave and yellow for neither concave nor convex)? Thanks a lot for reading this message, and thanks in advance. Jean Jacques

## Branches in numeric integration...

A colleague is trying to evaluate some contour integrals numerically using evalf(Int(f,t=0..1)). Unfortunately f involves square and higher roots and Maple is getting an incorrect answer because it is not choosing the branch for these roots continuously through the range of integration. Apparantly Mathematica has an option in numerical integration which forces a continuous choice of branch for the integrand. Is there any reasonably simple way to achieve the same with Maple? Thanks.

## listplot3d problem...

Hello, I am trying to do a 3d plot from 3 datapoints from a text file. I have the file DATA with 4000 data points in the following format: -1 -1 2 -1 -0.976522 2 -1 -0.952609 2 -1 -0.915507 2 ... Where columns respectivly are the x, y, and z values that I want plotted. I figured that this command should plot the points: listplot3d(readdata("DATA",3), axes=boxed, labels=[x, y, z]); I do get a graph here, but instead of plotting the points x, y, z, I get the x value correspoindng to the line number, a y value that seems to be the value of the y column + 2, and the actual z value that I want. So, my question is, how do I just plot the three values that I am inputting?