Numerical Solutions and chaotic behavior 1 Numerical Solutions and Chaos
A Taste of Code def derivs(y, tsoln): th, a, pt, pa = y tdot = (pt - (1 + cos(a)) * pa)/(2.0 - cos(a)**2) adot = pa - tdot * (1.0 + cos(a)) ptdot = -g*(2.0 * sin(th) + sin(th + a)) padot = -tdot * (tdot + adot) * sin(a) -g * sin(th + a) return np.array((tdot, adot, ptdot, padot)) Numerical Solutions and Chaos 2
A Boy’s First Computer Numerical Solutions and Chaos 3
Neolithic Computing Bendix G15 $60, tubes 2160 words of memory punched paper tape i/o optional dent in the front panel 10 char/sec typewriter Numerical Solutions and Chaos 4
Richard Hamming ( ) The purpose of computing is insight, not numbers. Numerical Solutions and Chaos 5
Begin with g = 0 (no gravity) Numerical Solutions and Chaos 6
numerical results (g-free) Numerical Solutions and Chaos 7 timeE
tip motion (g-free) Numerical Solutions and Chaos 8
Now turn on gravity Numerical Solutions and Chaos 9
numerical results (g active) timeE Numerical Solutions and Chaos 10
tip motion (g active) Numerical Solutions and Chaos 11
Chaos Numerical Solutions and Chaos 12
Edward Lorenz ( ) Meteorologist who contributed to chaos theory. Encountered pathological sensitivity to initial conditions in early weather prediction simulations. Published Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas? Numerical Solutions and Chaos 13
Lorenz’ Informal Definition Chaos: When the present determines the future, but the approximate present does not approximately determine the future. Numerical Solutions and Chaos 14
Some properties of chaos Numerical Solutions and Chaos 15
Numerical Chaos Numerical Solutions and Chaos 16
using numbers We generated two numerical solutions to the double pendulum with initial conditions that differed by one part in 1000 (0.1%). For each solution we computed the location of the tip of the pendulum, and then computed the distance, as a function of time, between the two tips. Numerical Solutions and Chaos 17
Tip offsets versus time Numerical Solutions and Chaos 18
Tip offsets versus time (log) Numerical Solutions and Chaos 19