Moved mathpixel to new repo and added new default animation

apps/pendlum.py

@@ -1,81 +0,0 @@
-#!/usr/bin/env python3.6
-import numpy as np
-import sys
-import os
-import time
-import colorsys
-
-Nx = int(sys.argv[1])
-Ny = int(sys.argv[2])
-N = 100
-iterations = 2
-try:
-    N = int(sys.argv[3])
-except:
-    pass
-
-def rk4(f, x, dt):
-    k1 = f(x)
-    k2 = f(x+k1*dt/2)
-    k3 = f(x+k2*dt/2)
-    k4 = f(x+k3*dt)
-    return x+dt*(k1+2*k2+2*k3+k4)/6.0
-dt = 0.08 
-m = 1
-l = 1
-g = 1
-
-def sq(x): return x*x
-
-def rhs(x):
-    phi1 = x[0]
-    p1 = x[1]
-    phi2 = x[2]
-    p2 = x[3]
-
-    dphi1 = 6/(m*l*l)*(2*p1-3*np.cos(phi1-phi2)*p2)/(16-9*sq(np.cos(phi1-phi2))) 
-    dphi2 = 6/(m*l*l)*(8*p2-3*np.cos(phi1-phi2)*p1)/(16-9*sq(np.cos(phi1-phi2)))
-
-    dp1 = -0.5*m*l*l*(dphi1*dphi2*np.sin(phi1-phi2)+3*g/l*np.sin(phi1))
-    dp2 = -0.5*m*l*l*(-dphi1*dphi2*np.sin(phi1-phi2)+g/l*np.sin(phi2))
-    return np.array([dphi1, dp1, dphi2, dp2])
-
-s = np.array([np.pi+0.1, 0, np.pi-0.1, 0])
-
-angles = np.linspace(np.pi, np.pi/3, N)+np.random.uniform(-np.pi/6/N, np.pi/6/N, N)
-angles = np.random.uniform(-np.pi/6, np.pi/3, N)+np.pi
-states = [np.array([np.pi, 0, a, 0]) for a in angles]
-
-def clamp(x, min_, max_):
-    return  max(min_, min(max_, x))
-
-buffer = bytearray(b"\x00"*Nx*Ny*3)
-
-def setpixel(x, y, r, g, b):
-    xi = int(Nx*(x+1.2)/2.4)
-    yi = int(Ny*(y+1.2)/2.4)
-    if xi < 0 or xi >= Nx or yi < 0 or yi >= Ny:
-        return
-    idx = xi+Nx*yi
-    buffer[3*idx+0] = r
-    buffer[3*idx+1] = g
-    buffer[3*idx+2] = b
-timestep = 0
-timefac = 0.03
-while True:
-    timestep += 1
-    for s, i in zip(states, range(len(states))):
-        phi1 = s[0]
-        phi2 = s[2]
-        x1 = np.sin(phi1)*l
-        y1 = np.cos(phi1)*l
-        x2 = np.sin(phi2)*l+x1
-        y2 = np.cos(phi2)*l+y1
-        h = 0.2*i/N+0*timestep*timefac/iterations
-        r, g, b = colorsys.hsv_to_rgb(h%1, 1, 1)
-        setpixel(x2, y2, int(r*255), int(g*255), int(b*255))
-        states[i] = rk4(rhs, s, dt/iterations)
-    if timestep > 10*iterations and timestep % iterations == 0:
-        #time.sleep(0.01)
-        os.write(1, buffer)
-