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## Re: DAE daspk solver problem

**From**: |
Sebastian Schöps |

**Subject**: |
Re: DAE daspk solver problem |

**Date**: |
Thu, 27 Oct 2016 00:29:52 -0700 (PDT) |

Lazy_Tom wrote
>* f(1) = xdot(1)-x(2);*
>* f(2) = m*xdot(2)+x(5)*x(1);*
>* f(3) = xdot(3)-x(4);*
>* f(4) = m*xdot(4) + x(5)*x(3) +m*g;*
>* f(5) = x(1)^2 + x(3)^2 - 1;*
I think there are a few typos, e.g., it should be -x(5)*x(3) in eq (4) but
this is probably not the issue here. You are trying to solve a very
difficult problem. This formulation of the pendulum is a DAE of index 3 and
afaik daspk can only deal with DAEs of index<3. There are many good books on
this topic. If you are looking for a good free ressource, you may want to
look at
https://www.mathematik.hu-berlin.de/~steffen/pub/introduction_to_daes_497.pdf
(page 2 and 13).
Seb.
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**DAE daspk solver problem**, *Lazy_Tom*, `2016/10/26`
**Re: DAE daspk solver problem**,
*Sebastian Schöps* **<=**
**Re: DAE daspk solver problem**, *Lazy_Tom*, `2016/10/27`
**Re: DAE daspk solver problem**, *Sebastian Schöps*, `2016/10/28`
**Re: DAE daspk solver problem**, *Bill Greene*, `2016/10/28`
**Re: DAE daspk solver problem**, *Lazy_Tom*, `2016/10/29`
**Re: DAE daspk solver problem**, *Sebastian Schöps*, `2016/10/29`
**Re: DAE daspk solver problem**, *Lazy_Tom*, `2016/10/29`
**Re: DAE daspk solver problem**, *Sebastian Schöps*, `2016/10/29`
**Re: DAE daspk solver problem**, *Lazy_Tom*, `2016/10/29`
**Re: DAE daspk solver problem**, *SunilShah*, `2016/10/28`
**Re: DAE daspk solver problem**, *Bill Greene*, `2016/10/28`