When Benoit Mandelbrot was still alive I sent him an email:

Hi,
I am writing to you because I have trouble understanding why
the covariance function in the Fractional Brownian Motion (FBM) is given by:

(t[i]^(2*H)+t[j]^(2*H)-abs(t[i]-t[j])^(2*H))/2)

I would be very grateful if you could please explain this to me in simple and step by step terms.
I understand simple ARIMA models (P(t)=P(t-1)+E(t) where E(t)=p*E(t-1)+r(t)) which have the
same...

No, I'm willing to bet it's about as random as flipping a coin.  You might say, huh?!  I think my theory is interesting but this isn't really a maple question although perhaps we can make it into one, it would be that much more interesting.  I haven't done so yet, but anyone is welcome to.

With practice, I can flip a coin and get 30 heads in a row no problems.  Now say for a roulette wheel operator who uses it constantly, you don't think he's gained...

Ok If R is the Cholesky decomposition of the Covariance matrix then I need:

i) Cov=R*R'
ii) R'=R

I can show that i) indeed holds but ii) does not seem to work. Why?

restart:
with(LinearAlgebra):
Cov := Matrix([[.1, .2], [.2, 1.3]]);
Ap := LUDecomposition(Cov, 'method' = 'Cholesky');

Cov = Ap.Transpose(Ap);
Ap = Transpose(Ap)

In feedback control I want to isolate the fraction that defines my system: output/input.

This cannot directly be done by solve, isolate or simplify  in any of my attempts. What I've done is to follow the solutions for the following problem: http://www.mapleprimes.com/questions/37686-Isolating-Variable-Quotient

But my problem is apparently a little more hairy, since solving...

I am looking for a way to check if multiple variables are different. Let's say I have 4 variables named a, b, c and d. You can do it with "a!=b and a!=c and a!=d and b!=c and b!=d and c!=d", but it quickly becomes impractical when you have more variables.

Can anyone shed some light on this?

Thanks!

Good afternoon

i have problem with that program, because it's too slowly, i can't plot and i I have difficulty in keeping the processed data vector.

this program in matlab 12 seconds delay.

Thank you for your help

final-robot-circuloI.mw

How to do this with Maple? Is it possible?

http://www.mapleprimes.com/ViewTemp.ashx?f=5794_1319135560/poissonHRI-1.jpg

Gracias

Hello, I'm trying to solve a very long system of equations, I've used PolynomialSystem and works, but it does not give me all of the solutions of the system. Im trying to do the solve comand, but after a few hours the mserver crasher and it needs to close, without having an output.

I woul really appreciate if anyone has a solution for this, I need to solve this and I'm getting stuck with this.

I'm attaching my worksheet  

Hi, I am very new to Maple and i was using Maple with a code that was running well when suddenly the rand() function that i use started to fail. and i get the error:

> rand();

Error, empty number

also i get many aditional errors in some sentences where i am addressed to some '?' simbols which are supposed to be in my sentendes.

has anyone gone trhough that? any help will be appreciated.

josep

I'm trying to do a least square estimation

with(plots);

q := array([892., 1012., 1060., 987., 680., 739., 809., 1275., 946., 874., 720., 1096.]);

p := array([1.23, 1.15, 1.10, 1.20, 1.35, 1.25, 1.28, .99, 1.22, 1.25, 1.30, 1.05])

lnx := array([seq([ln(p[t])], t = 1 .. 12)]);

lny := array([seq([ln(p[t])], t = 1 .. 12)]);

pointplot({seq([ln(p[t]), ln(q[t])], t = 1 .. 12)}, symbol = circle, axesfont = [TIMES, 14], labels = [x = ln(p), y = ln(q)])

Hi all! I have a list of data. I can use pointplot to plot them. Now, whatshould I do if I want to connect (join) these points toghether like an ellipse or rectangle or others form? For example:

S := [[1,1], [3,1], [4,2], [3,3], [2,3], [1,2]];

thanks  

Hi,

Can i use method=laplace to solve an ode with no initial condition?

ode := diff(phi2(x),`$`(x,2))-Omega0*diff(phi2(x),x)-k*R1*E1/C*sigma*phi2(x)-l^2*phi2(x)+2*R*k/C*N2*exp(Omega0*(x-1))*cosh(l*(x-1))*l*C2/exp(-l) = 0;

bcs:=phi2(1)=0,phi2(S0)=-N4*Phi;

sol := dsolve({ode, bcs}, phi2(x), method=laplace);

Thanks

I have uploaded to the Maplesoft Application Center a worksheet exploring the orbital dynamics of the recently discovered Kepler 16 system, where a planet orbits a double star. 

Your comments and suggestions will be appreciated.

Good night.

I have a problem with this error "Error, (in unknown) invalid input: `dsolve/numeric/lexorder` expects its 2nd argument, b, to be of type {indexed, name, numeric}, but received cos(t) "

help me please

final-robot-circul.mw

Hey,

I have one function that is consisted of several matrices.. The function is,

R := log(determinant(MCOV))+trace(multiply(SCOV, inverse(MCOV)))-log(det(SCOV))-2+Transpose(SM-TAU-multiply(L,K))&*inverse(MCOV)&*(SM-TAU-multiply (L, K));

where MCOV, SCOV, SM,TAU, L, K are all matrics. In a MCOV and L, there are symbols also..

I have tried to get...