## scatter plots...

Can anyone tell me how to work out correlation coefficients!!! I need it in very simple terms as I just dont get it ie if 2 variables has a correlation coefficient of .690 what does it mean?  Can someone explain it to me?  With thanks

## Gaussian Copula...

Does anyone know how to step-by-step set up a Gaussian Copula in Maple?

I know how to simulate cross correlated random variables by using the Cholesky Decomposition but the requirement that the

correlation matrix must be positive define (all eigenvalues +) is such a pain!

I know that copulas can easily be estimated in MATLAB but I have not seen one in Maple. Any ideas?

## looking for a continous anti-derivate for trig/rat...

I want a continous anti-derivate (cos(2*u*m)-alpha*u*sin(2*u*m))/(4*u^2+1)
w.r.t. u, for alpha and m Reals, 0 < u.

What I get with Maple in terms of Ci and Si jumps in m=0 (and for m=0 it
is not defined, due to Ci).

The best I got was

Si(-conjugate(v))-Si(v); eval(%, v=m*(2*u+I));
psi:= unapply(%, u,m);
chi:= (u,m) -> piecewise(0 <= m, -Ci((2*u-I)*m)+Ci(m*(2*u+I)),

## How to calculate the statistical quartile maple?...

Here I show the results of the statistical calculation of the quartile, by several methods. All show different results for the same input data.

## export RTF...

Hi everybody:

Concerning exporting a worksheet as RTF (Maple12, win XP) I note two things: a) if you use inline output things such as equal sign, arrow with "at 5 digits" text, etc. appear slightly higher than the rest of the expression. also some part of the output is chopped off. b) the labels don't export.

Are these things consistent with what you could currently expect from maple or am I missing something?

thanks

Dimitrios

## Quantum Mechanics...

Suppose that the Hamiltonian is invariant under time reversal:

[H,T] = 0.

Show that, nevertheless, an eigenvalue of T is not a conserved quantity.

v/r,

## plotting a 2xN matrix...

1. How do I take a 2xN matrix and plot it on a 2D graph by its columns?

2.How do I take a number n and a 2xN matrix and return the product of A^n with the 2xN matrix, where A is a 2x2 matrix?

3.How do I, using your two functions above, write a procedure which plots on the same graph the result of multiplying the 2xN matrix by A^n for n = 0,1,2..10. How do i cause these sequence of plots to be displayed as an animation?

## define_external : importing a Fortran subroutine p...

Hi,

I'm working on a computational physics project and prefer to use Fortran codes (compiled by MVS-9) with Maple power together.

In recent days I've changed some compiler options in MVS and unfortunatly (I don't remember the options) nothing works well as before.

For example, as I try to use a simple code like this:

## Welcome to How do I...with MapleSim...

This forum is the place for you to post all of your MapleSim questions.

## 3-D system: how many solutions?...

Hi there,

So my problem is to find the solution(s) of a 3-D system. I can get Maple to spit out a solution (at times), but I am looking for reassurance that this is indeed the solution (if unique, and if not what the other solutions may be). Increasing Digits makes Maple "lose" the solution and return a blank-- normal behavior? Looking at the 3-D plot of the system offers something to puzzle over.

I set up the system in  (x,c,q):

xd := x^.5-.1*x-c;
cd := (.5/x^.5-.1-q)*c;
qd := -(q-.2e-1)*(q-.3e-1)+(q-.25e-1)*(.5/x^.5-.1-q)*c/(x^.5-.1*x-c);

I look for a solution with fsolve:

Digits:=10: interface(displayprecision=10):
ss:= fsolve({xd,cd/c,qd}, {x,c,q}, avoid={x=0, c=0, q=0});
xs:=subs(ss,x): cs:=subs(ss,c): qs:=subs(ss,q):

Maple gives:

ss := {c = 2.399289639, q = .2511089584e-1, x = 15.97164840}

If I raise digits to 15, Maple can't solve it anymore. Perhaps this is normal behavior.

I'd like some reassurance that this solution is indeed a solution. Simply feeding the fsolve output back into the system will not work because of a division by zero:

eval(xd,{x=xs,c=cs,q=qs}); eval(cd,{x=xs,c=cs,q=qs}); eval(qd,{x=xs,c=cs,q=qs});

yields:

0.
-.9597158556e-10
Float(-infinity)

I decided to look at the 3-D plot. The plot of the system suggests that there may be several solutions.

The plot:

px:=implicitplot3d({xd}, x=0..25,c=0..5,q=0.02..0.05, numpoints=10000, plotopts, colour=brown): pc:=implicitplot3d({cd/c}, x=0..25,c=0..5,q=0.02..0.05, numpoints=10000, plotopts, colour=green):
pq:=implicitplot3d({qd}, x=0..25,c=0..5,q=0.02..0.05, numpoints=10000, plotopts, colour=blue):
display3d({pq}, orientation=[-25,70]);
display3d({px,pc,pq}, orientation=[95,90], projection=1);

The plot is not very clean, and no matter how hard I've tried, by turning it around and zooming near the Maple solution, it is not clear that there are no other solutions. (well perhaps it is clear from the equations themselves, but I couldn't work it out and resorted to the numerical approach)

## Rioboo's algorithm for real rational functions?...

Does somebody have a sheet covering that algorithm for continous
anti-derivatives of rational functions (Bronstein's book §2.8
"Integration of transcendental functions")?

Or can show me, how to extract it from Maple's library in case
it is there (and I guess Maple covers that ...) for explicite
use?

## Partial Fractions Finder...

This is a unique, powerful and useful tool that will help students do decompositions of rational functions. See the attached worksheet. Also, you can view an interactive video tutorial that shows you how to use the Partial Fractions Finder: (Ctrl + click on link below) Video Tutorial: Partial Fractions Finder

## Write a procedure...

Write a procedure

input:a polygon and a linear transformation

output :applying the transformation to the polygon

Find the coordinates of the linear transformation that would have  the a larger square to the pink (smaller) square.Apply the transformation to the blue square.