How to use Slopefied[] command associated with NSolveODE[]?

LPH shared this problem 5 years ago

Answered

Hi Murkle and developers,

I recently discovered the existence of NSolveODE[] command. It is a very powerful and interesting tool for the study of dynamical systems (see below)

http://wiki.geogebra.org/en/NSolveODE_Command

Unfortunately it seems the command Slopefied[] is no longer adapted to the new format above and gives an error in the cases proposed (i.e. pendulum case):

http://wiki.geogebra.org/en...

Is it possible to adapt the command Slopefied[] to the new format of NSolveODE[] command, or is there a method to obtain the slope field in the proposed cases? :confused:

Best regards, :wink:

Phil

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Comments (2)

balazs.bencze ● 5 years ago

Hi Phil,

Although I've found a problem in the wiki page (NSolveODE yields numericalIntegral1 instead of numericalIntegral1_1, I'm not sure if related) I couldn't find the example using the Slopefield[] command together with the NSolveODE (the pendulum example doesn't uses the Slopefield command).

Could you send an example, in which case Slopefield[] needs adaptation?

Best regards,

Balázs

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LPH ● 5 years ago

Hi balazs,

I couldn't find the example using the Slopefield[] command together with the NSolveODE (the pendulum example doesn't uses the Slopefield command).

This is precisely the problem: The command Slopefield[] works correctly with SolveODE[]. Just try:

SlopeField[2x / y]

But the command Slopefield[] doesn’t allow to use the format of equations used in NSolveODE[].

I try to get the phase portrait (OK for this) and the slope field (not yet) of the van der Pol’s oscillator below:

http://en.wikipedia.org/wik...

Cheers, :wink:

Phil

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