86 lines
1.7 KiB
Python
86 lines
1.7 KiB
Python
import numpy as np
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"""
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Class definition for physical atribute
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"""
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class Body:
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def __init__(self, mass, position, velocity):
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self.m = mass
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self.q = position
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self.v = velocity
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self.p = velocity*mass
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class System:
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def __init__(self, bodylist):
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self.bodylist = bodylist
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def Mass(self): #return total system mass
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mass = 0
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for body in self.bodylist:
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mass = mass + body.m
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return mass
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def COM(self): #return center of mass in cartesian np_array
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coord = np.zeros(3)
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for body in self.bodylist:
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coord = coord + body.m*body.q
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coord = coord/self.Mass()
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return coord
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def Lval(self,Lbodylist): #return angular momentum of body in bodylist
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comcoord = np.zeros(3)
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for body in Lbodylist:
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comcoord = comcoord + body.m*body.q
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comcoord = comcoord/self.Mass()
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comq = np.zeros((len(Lbodylist),3))
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i = 0
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L = np.zeros(3)
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for body in Lbodylist:
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comq[i] = body.q-comcoord
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L = L + np.cross(comq[i],body.p)
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i = i+1
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return L
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#def initialize(self):
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# initialisation mass
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m1 = 10
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m2 = 1
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m3 = 1
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# initialisation position
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q1 = np.array([0, 0, 0])
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q2 = np.array([1, 0, 0])
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q3 = np.array([2, 0, 0])
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# initialisation velocity
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v1 = np.array([0, 0, 0])
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v2 = np.array([1, 1, 0])
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v3 = np.array([2, 0, 0])
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star1 = Body(m1,q1,v1)
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star2 = Body(m2,q2,v2)
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star3 = Body(m3,q3,v3)
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Lbodylist = [star1,star2]
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array = np.zeros((len(Lbodylist),3))
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array[0]=star3.q
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tribody = System([star1,star2,star3])
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print("list=",Lbodylist)
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print(tribody.Lval(Lbodylist))
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