Consider the following lines:

eqs := {x - a*y,y - a*x};
sol := solve(eqs,y);

In general, sol will be NULL, but if a²=1 then the equations can be solved. How can such side relations be implemented in connection with solving?

PS: The above example is of course a grossly simplified one.

Note added: Perhaps it would be prudent to mention that the variable 'a' above is intended to be a symbolic place holder for some operator acting on some functions x,y, and having square equal to the identity map; it is not simply some algebraic number. The equations should thus be solved for x,y using a²=1, without having assigned anything to 'a' itself. For the simple example above, this can be done using the function eliminate, as suggested by Axel Vogt, but for more complicated cases, its success seems quite unlikely: for one thing, how can one determine, by looking at the set of equations, which variables can or should be eliminated?

I am using maple 13 to get the result of the einstein field equations,

with(tensor)

...

Estn := Einstein(metric, RICCI, RS);

displayGR(Einstein, Estn);

How can I put the result on an array element, so I can use it later on?

The following integral appears in the recent SEEMOUS 2016 competition:
Int( arctan(x) * ln(1+1/x^2), x = 0..infinity );

Maple 2015 can compute it, but with a little help.
What about Maple 2016?

How can I get maple to express the end result more compact/dense. Like for example in the picture, why can the program not just sum up all the fractions and everything in one number?

 when send email to technical support of maple?

i would like to encrypt email content with maple public key in gmail

Hi, I need help finding the index of a given element in a list?

Say I have A:=[2,4,6,8,10,12], I want something that can do something like this:

index(A,6) 
                      3

EDIT:

Thanks, and sorry if my questions are trivial but I'm (clearly) not great with maple.

Now say I had two lists:

A:=[5,10,15,20,25,30,35,40,45,50]

B:=[7,14,21,28,35,42]

How would I get maple to return the index of the first element in list B that matches an element in list A, and the index of said element in list A? 


So something (remotely) like:

FirstMatch(B,A)
                        B[5], A[7]

(So I'm not looking for the first case of A[i]=B[i]. I just want i, j where A[i]=B[j])

Hello,

So I want to create an image of the cusp catastrophe that looks like this 

but instead I have been getting this image where the discontinuity is plotted out to infinity

I have tried to split up the surfaces on either side of this but I haven't been able to display both on the same plot whilst using implicitplot3d. 
This is the line of code for the image, there't not much too it
"
with(plots);

implicitplot3d(x^4+x^2*z+x*y, x = -7 .. 7, y = -50 .. 50, z = -10 .. 5, axes = boxed, style = surfacecontour, grid = [60, 60, 60], orientation = [180, 8, 175], 'transparency' = .1);
"
If anyone could help or point me in the right direction that would be great.
Cheers,
Darryl A.M.

using the code generator assistant I entered the following function

p := proc (z::(float[8]))

local a::integer, accm::(float[8]), k::integer, k1::(float[8]), c;
c := Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], order = C_order, datatype = float[8]);
k1 := 1;
c[1] := evalf(sqrt(2*Pi));
a := 12;
for k to a-1 do c[k+1] := evalf(exp(a-k)*(a-k)^(k-1/2)/k1); k1 := -k1*k end do;
accm := c[1];
for k to a-1 do accm := accm+evalf(c[k+1]/(z+k)) end do;
accm := accm*evalf(exp(-z-a)*(z+a)^(z+1/2));
return accm/z
end proc

the code-generated julia code follows

function input(z)
c = [0,0,0,0,0,0,0,0,0,0,0,0]
k1 = 1
c[0] = (sqrt(2 * pi))
a = 12
for k = 1:a - 1
c[k] = (exp(a - k) * (a - k) ^ (k - 1//2) / k1)
k1 = -k1 * k
accm = c[0]
for k = 1:a - 1
accm = accm + (c[k] / (z + k))
accm = accm * (exp(-z - a) * (z + a) ^ (z + 1//2))
return(accm / z)
end

two things are wrong

1: no end after loop end

2: array index starts at 0, it should be 1 and of course the array references should reflect that

btw, it would be nice to be able to enter code tags like [code] code here [/code]

Hello everyone.  Let n be a positive number; I seek how to write the matrix Z\in M_{2^n,n} that is defined as follows:

for every i,j, Z_{ij}\in \{-1,1\}.

When I consider the 2^n rows of Z, I want to find ALL the possible sequences of length n with the entries +-1. A toy example, when n=2, is Z=\begin{pmatrix}1&1\\1&-1\\-1&1\\-1&-1\end{pmatrix}.

Thanks in advance;

Write a Maple procedure which takes any cubic polynomial [−3, 3] p −→ R and returns the following:

How i can plot of p and its tangent lines illustrating the nature of each critical point.

Demonstrate this in the instance that p(x) = 1/3 x^ 3 − 6/10 x^ 2 − 187/100 x + 1.

Any ideas how i can solve this?

I wonder if there is any way to sort expressions like

 to

also:

how to sort  to

Hello,

I'm sorry to bother you but I have a problem with the numeric resolution of a system of 3 differential equations. The system is as follows  : sysdif :=

As you can see the system is composed of 3 differential equations, and I enter initial conditions in the object "sysd". Then I try a numeric resolution by executing the following command (I give a value to parameters before)  :

Then Maple's answer is : Error, (in dsolve/numeric/process_input) missing differential equations and initial or boundary conditions in the first argument: sysdif.

I can't see where I'm wrong, does anyone notice something that could explain this error message ? There's no help page about this error so I ask the question here.

Thank you very much for your time if you answer this,

Louis

I noticed that Maple 2016 did not add entry in the start menu->All programs, after installing it on window 7, as all the other Maple releases did.  I looked everywhere and do not see it. This is very strange. Only time I had problem like this, where I install Maple but it does not show up in the start menu.

I did not have problem installing 2016, and I can use it fine.  But each time I need to start it now, I have to do start menu->Search and type Maple 2016, to find Maple 2016.

Is there a way to make it show in the start menu? Should I uninstall it and install again? Any one else had this problem on windows?

Using Maple 2016, windows 7, 64 bit. I see 2 problems allready. One is that long display do not wrap around as it does with Maple 2015. Second problem, I see strange characters inside the numbers displayed on the screen.  Here is 2 screens shots, same computation, one from Maple 2015 and one from Maple 2016. Both on same PC. Windows 7.

Notice also the result for 2016 do not wrap. I had to scroll to the right to see the full result.

Here is the code in plain text. Can someone verify if they get the same problem on Maple 2016?

V:=(m,n)->binomial(m-floor(1/2*(n+1)),m-n)+binomial(m-floor(1/2*(n+2)),m-n);
r:=V(2000,500):
r:=r/10^6:
r:=r/(60*60*24*365);

@Markiyan Hirnyk 

Thanks for helping.

(1) But how to find period using code?

(2) how did you determine n=29 ?

(3) I don't need sequence of numbers, but would like to extract the coefficients of exp(..) terms. For example in the follwoing expression, how to extract the coefficients: (note that the expression is missing one more term and i don't know how to fix?)