file management

lib/LeapFrog.py

@@ -0,0 +1,70 @@
+#!/usr/bin/python
+# -*- coding:utf-8 -*-
+"""
+Hermite integrator
+"""
+
+
+from os import system
+import numpy as np
+from lib.plots import DynamicUpdate
+from lib.units import *
+
+
+def Drift(dyn_syst, dt):
+    for body in dyn_syst.bodylist:
+        body.q = body.q + dt * body.v
+
+
+def Kick(dyn_syst, dt):
+    for body in dyn_syst.bodylist:
+        body.a = np.zeros(3)
+        for otherbody in dyn_syst.bodylist:
+            if body != otherbody:
+                rij = np.linalg.norm(body.q - otherbody.q)
+                body.a = body.a - (body.q - otherbody.q) * G * otherbody.m / (rij ** 3)
+        body.v = body.v + dt * body.a
+
+
+def LP(dyn_syst, dt):
+    dyn_syst.COMShift()
+    Drift(dyn_syst, dt / 2)
+    Kick(dyn_syst, dt)
+    Drift(dyn_syst, dt / 2)
+    dyn_syst.time = dyn_syst.time + dt
+    for body in dyn_syst.bodylist:
+        body.p = body.v * body.m
+
+
+def leapfrog(dyn_syst, duration, dt, recover_param=False, display=False, savename=None):
+    if display:
+        try:
+            system("mkdir tmp")
+        except IOError:
+            system("rm tmp/*")
+        d = DynamicUpdate(dyn_syst)
+        d.launch(dyn_syst.blackstyle)
+
+    N = np.ceil(duration / dt).astype(int)
+    E = np.zeros(N)
+    L = np.zeros((N, 3))
+    for j in range(N):
+        LP(dyn_syst,dt)
+
+        E[j] = dyn_syst.E
+        L[j] = dyn_syst.L
+
+        if display and j % 5 == 0:
+            # display progression
+            if len(dyn_syst.bodylist) == 1:
+                d.on_running(dyn_syst, step=j, label="step {0:d}/{1:d}".format(j, N))
+            else:
+                d.on_running(dyn_syst, step=j, label="step {0:d}/{1:d}".format(j, N))
+    if display:
+        d.close()
+        if not savename is None:
+            system("convert -delay 5 -loop 0 tmp/??????.png tmp/temp.gif && rm tmp/??????.png")
+            system("convert tmp/temp.gif -fuzz 10% -layers Optimize plots/{0:s}_dynsyst.gif".format(savename))
+
+    if recover_param:
+        return E, L