Timo Stienstra

[GSoC] Planar Joint

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#### References to other Issues or PRs Part of #21519 #### Brief description of what is fixed or changed Implements the PlanarJoint #### Other comments #### Release Notes * physics.mechanics...

[GSoC] Spherical joint

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#### References to other Issues or PRs Part of #21519 #### Brief description of what is fixed or changed Implements the SphericalJoint #### Other comments #### Release Notes * physics.mechanics...

Consistency in saving the velocity and acceleration in the physics.vector.point class

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After having several conversations over time we have come to the conclusion that it would be good to make a decision and also universally implement it. The following is the...

Null matrix can always be stacked

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While developing in sympy I stumbled upon the difference that within sympy [a null matrix can be stacked](https://github.com/sympy/sympy/blob/5c661af67a1e3c2168c0684aa9713b9ab6551ab1/sympy/matrices/common.py#L281). The issue within sympy about this problem was [#10770](https://github.com/sympy/sympy/issues/10770).

Speed up forcing vector computation in KanesMethod

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#### References to other Issues or PRs Implements the proposal from #24790 #### Brief description of what is fixed or changed Speeds up the computation of the forcing vector in...

Speed up KanesMethod _f_d computation

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When I was experimenting with the numerical stability in `KanesMethod` I ran into some extremely big expressions, this resulted in `KanesMethod` becoming rather slow. When profiling I saw that I...

KanesMethod numerical error due to LUsolve of the velocity constraints

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`KanesMethod` uses and [`LUsolve` ](https://github.com/sympy/sympy/blob/4fb6b42dd0941f05178aa570edf9ef61162ce960/sympy/physics/mechanics/kane.py#L252) to solve the velocity constraints. While this matrix is invertible it does cause numerical instabilities from time to time, caused by zero divisions. This problem...

Physics mechanics devel

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# PR purpose The current implementation of the `sympy.physics.mechanics` module is problematic in several ways. To support @brocksam's work for the CZI grant (specifically adding support for `biomechanics`) it will...

System implementation

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#### References to other Issues or PRs #### Brief description of what is fixed or changed This PR is part of the mechanics experimental development (#24234) implementing the `System` class...

Implement an abstract class for bodies

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#### References to other Issues or PRs Output of the mechanics experimental development (#24234) Implements parts of #24238 and #24699 #### Brief description of what is fixed or changed This...