## 415 Reputation

7 years, 352 days

## How to use animate (or explore) function...

Maple 2024

Hello

Here is the ODE

`sys := {diff(w(t), t) = y(t)*z(t), diff(x(t), t) = a*w(t), diff(y(t), t) = x(t)*z(t) + w(t), diff(z(t), t) = -x(t)*y(t), w(0) = w0, x(0) = x0, y(0) = y0, z(0) = z0}`

with initial parameters a=2, w0 = -0.727367040, x0 = -0.728244724, y0 = -0.237753623 and z0 = 0.014225402.

With these parameters I have no problem to plot the solution.

```nsys := subs({a=2,w0 = -0.727367040, x0 = -0.728244724, y0 = -0.237753623, z0 = 0.014225402},sys);

numsol := dsolve(nsys, numeric, method = rkf45);

vars:=[x,y,z,w];

with(plots):

col := [red, magenta, cyan, blue]:
display(
seq(
plots:-odeplot(numsol, [t, vars[i](t)], t=0..3, color=col[i], legend=vars[i](t))
, i=1..numelems(vars)
)
)
```

How to use animate (or explore?)  with a slider for each parameter (a,x0,y0,z0,w0)? And if I want to add a tfinal as well for the simulation (in place of 3)? ( I am newbie as far as using plot and related functions in Maple).

Many thanks.

## How to retrieve the coefficients of a tr...

Maple 2024

Hello

Consider,  as an example,  the following (simple) transcendental equation.

`alpha*((epsilon-1)*x+y-3*x*z-epsilon/3*x^3+b*sin(w)+3)`

How to retrieve the coefficients and the terms considering that the unknowns are x,y,z and w?   Something like [x,y,x*z,x^3,sin(w),1] and their coefficients.

many thanks

## Given that the solution of a PDE is know...

Maple 2024

Hello

I am trying to understand how to use Maple to solve a PDE.  Below it is a problem (Henon-Heilles system) where the answer is known.

```with(PDEtools);

infolevel[pdsolve]:=3:

declare(Hamil(x,y,u,v));

PDEHamil := u*diff(Hamil(x, y, u, v), x) + v*diff(Hamil(x, y, u, v), y) + (-2*x*y - x)*diff(Hamil(x, y, u, v), u) + (-x^2 + y^2 - y)*diff(Hamil(x, y, u, v), v) = 0;

pdsolve(PDEHamil)
```

Maple returns no solution, but one solution is:

```sH:=1/2*(u^2+v^2)+1/2*(x^2+y^2-2/3*y^3)+x^2*y;

simplify(eval(subs(Hamil(x,y,u,v)=sH,PDEHamil)));
0=0
```

What am I missing?

Many thanks.

## Help on how to solve (if possible) a PDE...

Maple 2024

Hello,

I need to check if Maple can solve a specific PDE. Since I don't know much about the PDEtools package, I wonder if a user familiar with it and experienced in solving PDEs could help me.

```with(PDEtools);
declare(u(x,y,z,w));
PDE1:=alpha*(y+b*(w))*diff(u(x,y,z,w),x)+(x+z-b*(w))*diff(u(x,y,z,w),y)-c*y*diff(u(x,y,z,w),z)+d*(y-x)*diff(u(x,y,z,w),w)=0;
Sol1:=pdsolve(PDE1);
```

Maple returns NULL as the solution. Any ideas on how to obtain a solution, if possible? In other similar PDEs, u(x,y,w,z) has a quadratic form.

Many thanks,

## How to retrieve the arguments of f_1 , t...

Maple 2024

Hello

I am trying to solve some PDEs using Maple.  In one of them, Maple returns

`SolL:= HL(x, y, z) = f__1(1/2*(2*sigma*z - x^2)/sigma, rho^2 - 2*rho*z + y^2 + z^2)`

How to retrieve only the arguments of f__1?

Many thanks

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