I was reading about Thomas M. Cover Universal portfolios.
earthchangesmedia.com/breaking/April2000/0418universal.htm

One of the contributing factors seem to be related to exponential growth.
Two sentences caughts my eye:

"With the universal portfolio algorithm, profits grows exponentially.
The average of exponential growth rates has the same growth rate as the maximum"

Testing a numerical implementation I want to access data, which are
suggested as maximal errors through plotting (with care) to examine
that in more detail (so plotting is considered just a help)

For univariate functions I am aware how to look into data pairs for
the command plot.

My function is bivariate and real valued.

P:= plot3d( f(x,y), ...) lets me save the result and 

  op(P);
  op(1,P);
  arr:=op(3, %);

  arr; Arr:=convert(%, Matrix);
  plots[matrixplot](Arr, axes=boxed);

hi im trying to do a pretty simple 2 eq system

and i get

> e1 := 1.74*10^(-15) = D*exp(-Q/(8.31*1473));

> e2 := 7.1*10^(-15) = D*exp(-Q/(8.31*1573));

> solve({e1, e2}, {D, Q});
Warning, solutions may have been lost
 

any help will be appreciated

In a previous thread here I was looking at working with a noncentral F distribution. I have since found out what I need to be doing is a bit different.

The theory is as follows:

So, The F(1-alpha, nu1,nu2) is actually a Quantile value of the central F distribution. In my case, I'm trying to find a minimum sample size where nu1=3 and nu2=3*n. I transform the Power Equation into a function of into a cumulative distribution question using the formula P(A>B)=1-P(A<=B).

Hello

I am trying to plot a 3d function, but there is a problem.

Here is a screenshot of the problem img130.imageshack.us/img130/6008/3dplotproblem.jpg

thank you

Hello everybody, please help me. I have a system of PDEs and I can't solve it. I have an error as:

"Error, (in pdsolve/numeric/par_hyp) Incorrect number of initial conditions, expected 3, got 2"

I want to obtain the exact (symbolic) solution of

240*t^3 + 144*t^2 - 135*t -52 =0

in the form  a+ b*I, where a, b are (symbolic) real numbers.

It is possible if I understand Wikipedia well.

"solve" gives "RootOf" and the "convert(......, radical)"  gives quantities such as

(9522 + 45*I* squarerootsymbol(226511))^(1/3)

Thanks.

Sorry for posting the question to two topics (here and there http://www.mapleprimes.com/forum/ihaveequationafterdsolvehowcaniuseonlyonepartitseewhensolutionbecomesequalsmth)

But it seems to me that it fits both of them.

________________

I have a differential equation.

ODE := diff(diff(x(t), t), t)+.2*(diff(x(t), t))-x(t) = sin(t)

ics := x(0) = .5, (D(x))(0) = 5

X1 := dsolve({ODE, ics})

So the solution is: 

I have a differential equation.

ODE := diff(diff(x(t), t), t)+.2*(diff(x(t), t))-x(t) = sin(t)

ics := x(0) = .5, (D(x))(0) = 5

X1 := dsolve({ODE, ics})

So the solution is: 

X1 := x(t) = exp((1/10*(-1+sqrt(101)))*t)*((111/404)*sqrt(101)+111/404)+exp(-(1/10*(1+sqrt(101)))*t)*(111/404-(111/404)*sqrt(101))-(5/101)*cos(t)-(50/101)*sin(t)

Now I need to find out when the solution becomes equal to 1.

But Maple of course does not understand when I write

Hi all

I'm having trouble with Maple and cancelling fractions properly. I will demonstrate. As you can see the method using sub and fractions doesn't work whilst directly copying it into a stacked fraction does. I can see that it must be to do with which fraction is the main one (largest bar) but if I put in my variables like they appear it changes and thus doesn't cancel properly.

I have also include the maple file with the actual problem in context if that helps.

Any help would be much appreciated.

I found the below text here :  scienceblogs.com/goodmath/2008/07/back_to_math_solving_zerosum_g.php

My question is how can I set up this problem in Maple ?!

The objective function should be: min(E(H1), E(H2), E(H3))
constraint:  Σp_i=1, and ∀i: 0≤p_i≤1.
solution: p₁=0.57, p₂=0.17, p₃=0.26.

Hello,

I have an expression y, it comes from a calculation. I would like to simplify the argument of arctan in the expression using Maple. (This can be a part of a complicated expression, so I 'd like to automatize this procedure).

Assumptions: s0>0, w>0

y:=cos(w*t-arctan(2*s0^3*w, -s0^2*(-s0^2+w^2)));
 

Thank you for your help in advance.

Is there already a command to convert a higher order DEQ to a set of first order equations? Coeffs may be not neccessarily constant or polynomial in the independent variable. Example:

y'''-2*y''+x^2*y'+sin(x)*y-1=0

should convert to

X'=A*X+B

with A,B matrices and X,X' vectors of length 3
 

How do I make a phase plane diagram in Maple given the system needs to be solved implicitely? It's the implicit solving that is throwing me the curve ball....Any help is greatly appreciated! Thanks,

Nathan

Hi,

I am given the differential eqn : 4x'' +3x'+kx=0  with initial conditions  x(0)=0 and x'(0)=1

then I'm asked to:

display a Hooke's constant k>0 such that the solution x(t) is under-damped. Check that    x(t)=0  for infinitely many t>0. Display the exact solution x(t) obrained by maple methods.