MaplePrimes Questions

I need to maximize two multivariate objective functions (f(x1,y1,z1,t1) and g(x2,y2,z2,t2)) with inequality and nonnegativity constraints (x1, x2>0 and y1, z1, t1, y2, z2, t2 >=0). I am looking for parametric not numerical solutions.


What is the best way to find the solution to such a problem using maple?

Hi:

i will plot the following equation so that the horizontal axis in terms of omega and vertical axis in terms of a,but i can not do it,can i help me?

equation:

 

Hi ,

I would like to resolve the Kortweg and de Devries equation :

> KDV2:= diff( u(X,T), T)+ 6*u(X,T)*diff(u(X,T),X)+ diff(u(X,T),X$3);

 

I used pdsolve but I have a problem to enter the IBC :

I want

u(infinity, t) =0
u( -infinity, t )=0

u ( x, 0 ) = 1


So I did :


> SOL:=pdsolve(diff( u(X,T), T)+ 6*u(X,T)*diff(u(X,T),X)+ diff(u(X,T),X$3)=0,{u(-10, T) = 0, u(10, T) = 0, u(X, 0) =1},numeric,time=T,range=-10..10);

 

But it doesn't work.

( I remplace infinity by 10 because then I want the graphic representation of the solution )

Could you help me please ?  

Hi,

 

I am completely new to Maple (and this kind of software in general).

I am just on my first steps of learning...but I quickly noticed, that if I write Pi and hit enter, I do not get

the well-known greek Pi-symbol. I get an ordinary "p" as the result.

I checked the greek-palette...nearly all items in this palette are ordinary letters.

Does anyone have an idea whats wrong?

BTW: I don`t know if it could have to do with that, but I use a german windows 7 installation.

 

Thank you,

regards,

Kai

Hi

I want to create a linearied model for a single or multi degree of freedom vibration system by MapleSim. i faced a lot of problem such as causalize ports, i search the user manual but i didn't find it useful. i attach a very simply one degree of freedom vibration system. i wondering if every one create a linearized model for it. my final goal is governing the equation and determine the natural frequency with nyquist plots. i have mapleSim 6.2 and Maple 17. Thanks

 

prob1.msim

Hello,

restart:

F+(1/4)*(4*(-Lambda)^(3/2)*h*m^2-2*sqrt(-Lambda)*exp(Lambda*h^2*m^2)*h*m+sqrt(Pi)*erf(h*m*sqrt(-Lambda)))/(m^2*(-Lambda)^(3/2)) = 0;

how to solve this for m for real roots, where the rest are constants with Lambda>0.

 

 

Hi:

I have a curve(plot) in Maple and i should find the math equation for it,everybody can help me how to find it?

 

AOA... I want to solve the following system in maple pl help

 

sys_ode := diff(y(eta), eta, eta, eta)+3*y(eta)*(diff(y(eta), eta, eta))-2*(diff(y(eta), eta))^2+x(eta) = 0, diff(x(eta), eta, eta)+3*Pr*y(eta)*(diff(x(eta), eta)) = 0

ics := y(0) = 0, (D(y))(0) = 0, (D(y))(infinity) = 0, x(0) = 1, x(infinity) = 0

Help.mw

Dear all;

Please give me few minutes to correct the output of this procedure.Many thinks. 
We will solve the waves equations: diff(f(x,y,t),t$2)=c^2*( diff(f(x,y,t),x$2) +diff(f(x,y,t),y$2));  where (x,y,t) in [0,1]*[0,1]*[0,T] using finite difference.  With Initial boundary conditions: [u(0,y,t)=u(1,y,t)=0],   [u(x,0,t)=u(x,1,t)=0],  [u(x,y,0)=f(x,y),   diff(u(x,y,0),t)=g(x,y)]... The code is done and perfect but....The output of this procedure is Nothing. How can I plot the solution...

f:=(x,y)->x*(x-1)*y*(y-1);
g:=(x,y)->0;
analytical_sol:=proc(dx,dy,dt,Tf)
local Ft, Fx,Fy,x,y, c1,c2,c,j,k,i,u;
Ft := floor(Tf/dt)+1;
Fx := floor(1/dx)+1;
Fy := floor(1/dy)+1;
x:=[seq(0..1,dx)]:
y:=[seq(0..1,dy)]:
c1 := (c*dt/dx)^2;
c2 := (c*dt/dy)^2;
#Initial position
for j from  1 to Fx do  
   for k from 1 to Fy do
  u[j,k,1] := f(-dx + j*dx, -dy + k*dy) -dt*g(-dx+j*dx, -dy + k*dy);
   u[j,k,2] := f(-dx + j*dx, -dy +k*dy);
end do;
end do;

# Boundary values j=1
for i from  1 to Ft +1 do
      for k from 1 to Fy do
         u[1,k,i] := 0;
      end do;
      for k from 1 to Fy do
         u[Fx,k,i] := 0;
      end do;

     for j from 1 to Fx do
         u[j,1,i] := 0;
      end do;
   
   for j from 1 to Fx do
         u[j,Fy,i] := 0;
      end do;
end do;

for i from 3 to Ft + 1 do
  for j from 2 to Fx-1 do
    for k from 2 to Fy-1 do
u[j, k, i] := 2*u[j,k,i-1] - u[j,k,i-2] + c1*(u[j+1,k,i-1]-2*u[j,k,i-1]+u[j-1,k,i-1]) + c2*(u[j,k+1,i-1] - 2*u[j, k, i-1] + u[j,k-1, i-1]);
end do;
end do;
end do;
return Matrix([seq([seq([seq(u[i,j,k],i=1..Fx)],j=1..Fy)],k=1..Ft)]):
end proc:

## Try the test
f:=(x, y) -> x (x - 1) y (y - 1)
g:=(x, y) -> 0;
analytical_sol(0.1,0.1,0.1,2);
                      

Hi:

i have a problem,every body can help me?

my equations:

 

Hello,

As a means of encoding information, I'm working with nested array objects (I had originally used lists, but they became too large and Maple suggested that I use arrays). The nesting should be at most four deep, but the nested arrays can have varying lengths. In order to work with the arrays, I have a series of procedures that manipulate a given array and update the existing array object to contain the result. The issue that I have is that one of my procedures needs to simultaneously use both the original array and a modified version of the array, but once the modification is performed, the original version no longer exists.

Ultimately, my issue boils down to this: is there a clean (or messy, I'm not picky) way to duplicate an array so that there are two copies of the array in memory? Just writting Array2 := Array1 just creates another pointer to the same array in memory from what I can tell, so that doesn't work. There is a function copy, but it doesn't seem to work on nested arrays. 

For example, running the following does not modify Array2.

Array1 := Array([Array([1, 2]), Array([3, 4])]);
Array2 := Array([Array([1, 2]), Array([5, 6])]);
copy(Array1, Array2);

Indeed, neither does

Array1 := Array([Array([1, 2]), Array([3, 4])]);
Array2 := Array([Array([1, 2]), Array([5, 6])]);
copy(Array1(2), Array2(2));

Unfortunately, the latter case would seem to mean that I can't just write a procedure to recurse through my layers of arrays and copy piecewise either.

Thanks in advance for any help.



Can anybody tell me what I'm doing wrong?
Or does anybody have some tips for things like this? (Things like this occur often)

Stephan

Hello,

Anyone can help me with the problem ?

I want to solve b1..b50

> restart; with(plots); with(LinearAlgebra); with(Statistics);
> m0 := proc (t) options operator, arrow; 1-exp((-1)*t*.5) end proc;
t -> 1 - exp((-1) t 0.5)
> m := proc (t) options operator, arrow; (1/(1+exp(-t+5))-0.67e-2)*1.0067 end proc;
/ 1 \
t -> |--------------- - 0.0067| 1.0067
\1 + exp(-t + 5) /
> n[max] := 10; delt := .2; n := n[max]/delt;
10
0.2
50.00000000
> T := Vector(50);
> b := vector(50); evalm(b);

> for i from 2 to n do T[i] := T[i-1]+delt end do;
> fun := proc (t) options operator, arrow; add(b[i]*m0(t-T[i]), i = 1 .. n) end proc;
> fun(t);
> fu := vector(50);

> for x to 49 do fu[x] := fun(x*delt) = m(x*delt) end do;
> s := solve({fu[1 .. 50]}, {b[1 .. 50]});

 

 

Thanks,

gerst

Hello,

sometimes I observe extreme delays when simply entering a variable name like fooBar; right after starting a Maple session. This happens when the current directory contains a file with that name, because Maple automatically loads this file.

For example, if I create an empty file fooBar.m and start a Maple session,

> fooBar;
Error, `./fooBar.m` is an incorrect or outdated .m file

raises an error. More often however, I have some huge Maple files in the working directory and whenever I use (by chance) a variable name in the Maple session that matches a filename, Maple tries to load the corresponding file.

Is there a documentation of this behaviour and a possibility to stop this automatic loading of files?

Thanks,

Erik

When trying to solve a set of partial differential equations, I always get the following error. I don't know what it means. Can somebody help me?

 

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