gpasmit

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10 years, 119 days

MaplePrimes Activity


These are replies submitted by gpasmit

@Preben Alsholm 

Thanks for your reaction. Yes, Sol=Eq75. Sorry for the confusion..... The code should be:

> Eq75 := dsolve({dsys, ini}, {phix(t), phiy(t), phiz(t), thetax(t), thetay(t)}, numeric, output = listprocedure, range = 0 .. ts)

> odeplot(Eq75, [t, Z2], 0 .. ts, numpoints = 100)

The code solves rigid body motion. Z2 is the z coordinate of a point on the rigid body and can be expressed as Z2=f(t,phix(t), phiy(t), phiz(t), thetax(t), thetay(t)). 

What I want to do is store the value Z2 at t=ts after running the simulation for t=0..ts. How can I call upon this value? The odeplot command can.......

desired value:= Z2(ts) doesnt work anyway...

Kind regards, Gerben

Hi Axel!

Thanks for your top tip! Using fsolve instead of solve provides a numerical solution for me. My problem is solved!

Best regards.

Hi Axel!

Thanks for your top tip! Using fsolve instead of solve provides a numerical solution for me. My problem is solved!

Best regards.

Thanks for you advice rlopez. It helped me quite a bit. Still maple is struggling with providing a solution.

When I looked for a numeric solution, I gave a positive value to y1 and y2. Maple still gives a solution with RootOf and _Z because there are solutions for a >0 and for a< 0. I need the solution for a positive a. There is only one solution for this positive a. How do I get maple to solve this?

Thanks in advance!

Thanks for you advice rlopez. It helped me quite a bit. Still maple is struggling with providing a solution.

When I looked for a numeric solution, I gave a positive value to y1 and y2. Maple still gives a solution with RootOf and _Z because there are solutions for a >0 and for a< 0. I need the solution for a positive a. There is only one solution for this positive a. How do I get maple to solve this?

Thanks in advance!

Ok, I know know that the RootOf is used because of the asymptotes in the arccosh. However y1 and y2 are positive, and thus ((y1+a)/a) > 1 and ((y2+a)/a). So we are working to the right of all asymptotes and there should be one solution. How do I let the solver take these assumptions?

Maple sais: 

> assume(a > 1);

> solve(x, a);

Warning, solve may be ignoring assumptions on the input variables.
 
How do I get Maple to look at this one existing solution?!
 
> x := a*arccosh((y1+a)/a)+a*arccosh((y2+a)/a);

/y1 + a\ /y2 + a\
a arccosh|------| + a arccosh|------|
\ a / \ a /

> solve(x, a);

/ /y1 + _Z\ /y2 + _Z\\
RootOf|arccosh|-------| + arccosh|-------||
\ \ _Z / \ _Z //
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