@dharr You are right

@Carl Love 

A[..,-[$n]];
Error, invalid `$` operator
      Typesetting:-mambiguous(A(period;&periodcommauminus0

        (Typesetting:-mambiguous(dollarn, 

        Typesetting:-merror("invalid `$` operator")))))

A[-[$n]];
Error, invalid `$` operator
 

@Carl Love Sure, sorry

I am really a beginner ...

Thats is very useful for my work, thanks!

Thanks, that is exactly what I want, even if I am not able to understand the command

U:=U[..,p]

But I have learned the magic function "fnormal", thanks!

Just a question more:
can I get the (real) eigenvalues (and therefore the correspondig eigenvector) in decreasing order?

It works, thanks!

My matrix is a covariance matrix, so I cannot add the option shape=symmetric.

Thanks, they works!

For some reasons I need to name my variables x[1], x[2], ...

What if I don't know how many variables for the function f? That is, could I generalize the definition of Gf without knowing a priori how many variables there are?

@Preben Alsholm 

Right, thank you

@Preben Alsholm please, could you explain me what is "Maple notatio a.k.a., 1D input" and how can I set it? Thanks

Why crash and not an error message?  Moreover, look at this: why 22?

Download edges.mw

Clear

I was hoping that gcd between polynomials took the same time as numbers, actually 0 seconds :-)

Thank you

The cpu time is now 18 s, what does it mean?

Thanks,

as you can see r is the same in our computation, so I believe for p and q. 

My pc is an Intel Core i5, 2.7 GHz, 8 GB RAM; the ratio between our times is almost 60. 

I don't know if that could be the problem.