ProfGhristMath

@robertghrist

illustrating & animating mathematics; penn professor; paterfamilias

philadelphia, pa
Vrijeme pridruživanja: kolovoz 2008.

Medijski sadržaj

  1. prije 17 sati

    working on a new project...

  2. 20. sij

    he was socially awkward in that clearly-brilliant way. we just all thought he was weird. then, one day, there was an announcement for a research talk in the math department that had a funny picture: (image credit )

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  3. 12. sij

    this semester, i am teaching multivariable calculus for engineers , using materials from the Calculus BLUE Project, a video-text on youtube. you can check out the (updated for 2020) trailer here...

  4. 12. pro 2019.

    like all things, this semester has come to an end... final lecture of my applied dynamical systems course

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  5. 10. pro 2019.

    just won the Carlitz-Zippin prize for best thesis in math at Penn, for work on Hodge Laplacians for cellular sheaves...! – mjesto: David Rittenhouse Laboratory

  6. 8. pro 2019.

    gravitational 3-body problems are great for chaotic dynamics. one of my favorites is the sitnikov system: given two equal massive bodies rotating about one another on ellipses, add a third tiny mass perfectly poised between them. give it a kick & what happens?

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  7. 6. pro 2019.

    the latest video by on dynamical systems features a few of my recent animations :-)

  8. 5. pro 2019.

    surprise! twitter video compression sucks... for a decent (and embeddable) version of this vid, go to the original on YT:

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  9. 5. pro 2019.

    one of the things you notice when you study chaotic dynamics in 2-d maps is the resemblance to mixing of fluids. the stretching & folding mechanisms are very similar.

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  10. 3. pro 2019.

    the poincare map of this system -- the first-return map obtained by slicing along a transverse disc -- has lots of interesting dynamics, including horseshoes.

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  11. 3. pro 2019.

    the periodically-forced duffing oscillator induces a flow on the solid torus with some lovely chaotic dynamics. by following a set of initial conditions in the plane over time, you can see the stretching & folding lead to chaos.

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  12. 1. pro 2019.

    this week in dynamical systems: examples of chaotic systems... i'm going to review one of my favorite -- the forced duffing oscillator. here is a physical simulation of it using springs to model the double-well potential.

  13. 28. stu 2019.

    Did the evening end in arm wrestling? Yes, yes it did.

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  14. 28. stu 2019.

    The desserts were especially nice, thanks to the 12yo who made chocolates...

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  15. 28. stu 2019.

    We had about eighteen students who had no way of getting home show up.

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  16. 28. stu 2019.

    A view of the appetizer course... Baked a dozen loaves of bread.

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  17. 28. stu 2019.

    Having a great time hosting students at my home for Thanksgiving... For some of them, it's their first Thanksgiving ever!

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  18. 26. stu 2019.

    today in dynamics class we learned about generalizations of the smale horseshoe map to maps with a *markov partition* defined via horizontal and vertical strips. these lead to subshifts of finite type & lots of cool theory...

  19. 25. stu 2019.

    twitter is going to compress this into mush, i'm sure. there is a better quality version up on youtube:

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  20. 25. stu 2019.

    the invariant set of the smale horseshoe is obtained by intersecting all the horizontal & vertical strips in the square under iterations of the map & its inverse. this type of set is a cantor set. it looks like dust, but is uncountably infinite.

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