MaplePrimes Questions

Hi All, 

I am working on a numerical simulation of a system of ODEs that blows up when I do a numerical solution. One of my advisors says to multiply  the ODEs in my system by -1 to reverse the role of the eigen values. I only vaguely understand this. Would you be able to point me in the right direction to figure this out? When I do this (-1 in front of two of the ODEs), my results are much more stable. I will attach the ODE system here. The parameter values follow.

 Thanks for any input,

Steve

 > Restart;

How can one avoid getting a > at the beginning of each line when pasting in several lines of Maple code taken from some other word processor?  I am sure this has been answered many times, but I cannot find the answer now.

Why can I only get the solution  -(-y + 2 x) ^3  (y + 2 x)  from 2) and not from 1).

I am doing the same thing in both of them but from 1) I get "Warning, solutions may have been lost" when Itry to solve for _F1

I want to go from A-B-C with commands (as in 1) ) without having to retype the expression

1)restart;

Hi all,

In Maple, I am integrating a function involving the "erfc" function,

the final integral result has no explicit form, but should be able to
representted as a "\Phi(.)" function, where the "\Phi(.)" is the Gaussian
distribution function (cumulative).

Is there a way to force the following integral to output in the form of
"\Phi(.)" in Maple?

Thanks

I'm attempting to find where the two peaks are given the following expression.

g(x,y):=(3 x^(2)*y^(2)+4 x^(2)*y+21 x^(2)-4 x*y^(2)-72 x*y-128 x+21 y^(2)+128 y+297)/((x^(2)+2 x+2) (y^(2)-2 y+2) (x^(2)-8 x+17) (y^(2)+8 y-17)):

There are two peaks found by viewing the graph of the expression above.  I've tried using the second derivative test, fsolve with no success. 

This is the command for fsolve i'm trying to use:

fsolve({(D[2](g))(x, y), (D[1](g))(x, y)},{x = -1.5 .. -.5, y = 1.7 .. 1.8})

Bonjour,

J'ai une erreur lorsque j'essaie de résoudre un système d'équation différentielle : "Error, (in DEtools/convertsys) unable to convert to an explicit first-order system" et lorsque je simplifie le système j'ai une erreur : "Error, (in dsolve/numeric/DAE/checkconstraints) the initial conditions do not satisfy the algebraic constraints".

Merci d'avance pour votre aide

Hi

During a longish run (memory usage gets to about 1815M in 583s ) the loop terminates with the error message

" Kernel connection lost

Hi everybody,

I've got a numerically computed 2D free energy profile given by a set of 3D points (x_n,y_n,E(x_n,y_n)). I'd like to obtain a fit to those points given by some sufficiently smooth analytical function E(x,y) and subsequently compute the critical points (i.e. local minima, maxima and saddle points). Does anyone know if there is any specific package to do this in Maple 8 (or higher) or else what is the best strategy to do so? Thanks in advance.

Dear  Maple World members,

 

I have a problem and I do not know how to solve this equation with Maple. If anyone can help me, that will a huge gift for me :)

{ [ dy/d(t) ]  / [ dx/d(t) ] } = e*[  ( a + b* y(t) + c* x(t) + d* x(t)* y(t)+ f *y(t)^2 )  / ( a + b*x(t) + c*y(t) + d* x(t)*y(t) + f* x(t)^2 ) ]

initial conditions :

at   t = 0,   x(0) = Xo, y(0) = Yo

 

Hi, i have the following equation system, for which i  already know the solution.

restart:

s1:=(r1*r2-1/(400000000*c1*c2))*(r1+r2)/((r1+r2)^2+(-1/(20000*c1)-1/(20000*c2))^2)
+(-1/20000/c1*r2-1/20000*r1/c2)*(-1/(20000*c1)-1/(20000*c2))/((r1+r2)^2+
(-1/(20000*c1)-1/(20000*c2))^2) = 611.0987791:

s2:=(-1/40000/c1*r2-1/40000*r1/c2)*(r1+r2)/((r1+r2)^2+(-1/(40000*c1)
-1/(40000*c2))^2)-(r1*r2-1/(1600000000*c1*c2))*(-1/(40000*c1)-
1/(40000*c2))/((r1+r2)^2+(-1/(40000*c1)-1/(40000*c2))^2) = -8334.070796:

In Maple 11, using labeldirections = [horizontal,vertical] was enough to display the y-axis label vertically.

But in the Maple 12 version this no longer changes the label to vertical, it still displays as horizontal and just cuts off the remainder of the label.

Has there been a notation change?  How can I now display the label vertically in the new Maple 12?  Thanks.

How do I put a number, as an example: 987654321 so that all the digits are in a list?  Say I want to pull out the 7th digit, which in this example happens to be 3.  Or let's say I want to find out what the 473rd digit in Pi is.

it would be of a great help if anyone share the companion CD of

 By Artur Portela, A. Charafi

 

thanks

I have a set of 2nd order nonlinear differential equations which I solve numerically. 

odeplot plots the numeric results of the function and first derivatives just fine.

I was wondering if there is anyway to plot second derivatives.

odeplot treats a 2nd derivative as zero.

Although, I don't know  for sure, I believe the RKF45 routine computes them during the integration. Any way to store them?

Any ideas are appreciated.

Thanks

 

 

I have Maple 11 on WINXP
my CPU usage never goes up over 50%. the software is too low.
how can i eliminate the CPU usage Limitation?
One of my friends said that i can use kernelopts() but i don;t know how to use it!

please help me.

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