I have data organized in a Matrix from which I want to select a sample based on a certain (simple) criterion, e.g. no cell in the first column to be negative.

I was quickly able to find a way to do it, inspired by a method Preben Alsholm used in a recent mapleprimes post.

But, I wondered, is that the most natural approach? So I quickly found another approach and compared them.

Any other suggestions welcome. Particularly methods that could...

Hello,

I am very new to maple. I am trying to determine x, y, z and the intersection the following tori:

((x * cosθ _j+ y * sinθ_j -r)² + (x * sinθ_j - y * cosθ_j -r)² + z² + a² - b² )² - 4 * a² * ((x * cosθ _j+ y * sinθ_j -r)² + z²) <= 0

for j = 1,2,3.

Hi

I try to solve following equation with the "solve" command, but an error "Warning, solutions may have been lost" is appered. tell me how can I solve this problem.

tnx

solve(-2.711505682*x-7.65*ln(3-x)-3/8*x^3+8.422482772=0 , x); 

Dear Primers

I have an exponantial equation of the form below:

eq161 := 1/2*alpha^4*(-2*exp(-1+1/2*(4*alpha^2+1)^(1/2)+1/2*(-4*alpha^2+1)^(1/2))*(4*alpha^2+1)^(1/2)+2*exp(-1+1/2*(4*alpha^2+1)^(1/2)-1/2*(-4*alpha^2+1)^(1/2))*(4*alpha^2+1)^(1/2)-2*exp(-1+1/2*(4*alpha^2+1)^(1/2)-1/2*(-4*alpha^2+1)^(1/2))*(-4*alpha^2+1)^(1/2)+2*exp(-1-1/2*(-4*alpha^2+1)^(1/2)-1/2*(4*alpha^2+1)^(1/2))*(-4*alpha^2+1)^(1/2)+2*exp(-1+1/2*(-4*alpha^2+1)^(1/2)-1/2*(4*alpha^2+1)^(1/2)...

I have been trying to obtain a 3D plot of f9x,y)=(x+y)e^(-x^2-y^2) and it keeps outputting  "warning unable to find numerical values for the in the region....blah blah blah"

Here is my call sequence

> plot3d((x+y)*e^(-x^2-y^2), x = -1.7 .. 1.7, y = -1.7 .. 1.7);
Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct

Anyone know what to do? ...

Can I install both 32 and 64 bit version on one PC? (64 bit in Program Files and 32 bit in Program Files (x86))?

If so, does it mean  I will need to use a second license? Not a problem, my Office version is 32 bt and have Maple 64 bit installed and I want to use Excel.

That is, something that will plot a bunch of rectangular boxes in 3d, instead of a bunch of rectangles in 2d.  Thank you.

Download problem_for.mw

I use some codes to find the coefficients of given functional expressions. But in the procedure of operation, "Error, invalid 'if' statement" is showed. How can I do to solve the error?
If this structure of code can't find the coefficients, how to get the coefficients?

P.S. the coefficients of given functional expressions like this:

given Ex:=a*x+b*y-d*z+e*y-f*x-m*z,

We are looking for someone that can develop some maple scripts for us. Must have some chemical engineering knowledge.

contact us: smne33@hotmail.com

regards.

When using the command "for", the results are placed in a column,such as if we input
for i from 1 to 3 do  i end do, the results are showed as

1

2

3.

This style is not convient to use for following computation. So how to put all results into a list or set ?

Can anybody explain why the same dsolve-command gives the correct results in Maple 13 and an unexpected complex result in Maple 15?:

Download problem1.mw

Give a polynomial a*x+b,We can use the command "coeff" to get a coefficient of x. Unfortunately the command does not work for functional work. I have a comlicated functional expression, and want to get the coefficients of some given basical term. How can I do to get the coefficients?

arclengthtrig.mw

Each time I try to appriximate it 5 decimal places it returns something else.

f(x):=((e^-ax^2)-bxln(1+x^2))/(2+x^2+csin(Pi*x))

i have defined a,b and c. (all randoms numbers between 0 and 1 )

But when i try to plot it

plot((f(x)), x=-4..4) i get ( warning unabe to evaluate function to numeric values ion the region)

also i can plot the graph even without a range included ???

What am i doing wrong, have i defined f(x) right. thanks in advance

also i can plot the graph even without a range included ???

I have a peace of a programm of finding the shortest way in graph! And I need to animate this way! Help please! 

This is a code of programme:

> restart: with(networks):
> new(G): n:=6:
> addvertex(i$i=1..n,G); 
1, 2, 3, 4, 5, 6
> addedge([seq([i,i+3],i=1..3),[1,2],[2,3],[4,5],

> [5,6],[1,5]],weights=[12,16,20,11,15,13,14,26],G):
> draw(Linear([1,4],[2,5],[3,6]),G);

 > T:=shortpathtree(G,1):