def _external_force(x,t,pot):
dim= len(x)
if dim == 3:
#x is rectangular so calculate R and phi
R= nu.sqrt(x[0]**2.+x[1]**2.)
phi= nu.arccos(x[0]/R)
sinphi= x[1]/R
cosphi= x[0]/R
if x[1] < 0.: phi= 2.*nu.pi-phi
#calculate forces
Rforce= evaluateRforces(R,x[2],pot,phi=phi,t=t)
phiforce= evaluatephiforces(R,x[2],pot,phi=phi,t=t)
return nu.array([cosphi*Rforce-1./R*sinphi*phiforce,
sinphi*Rforce+1./R*cosphi*phiforce,
evaluatezforces(R,x[2],pot,phi=phi,t=t)])
elif dim == 2:
#x is rectangular so calculate R and phi
R= nu.sqrt(x[0]**2.+x[1]**2.)
phi= nu.arccos(x[0]/R)
sinphi= x[1]/R
cosphi= x[0]/R
if x[1] < 0.: phi= 2.*nu.pi-phi
#calculate forces
Rforce= evaluateplanarRforces(R,pot,phi=phi,t=t)
phiforce= evaluateplanarphiforces(R,pot,phi=phi,t=t)
return nu.array([cosphi*Rforce-1./R*sinphi*phiforce,
sinphi*Rforce+1./R*cosphi*phiforce])
elif dim == 1:
return evaluatelinearForces(x,pot,t=t)
def _linearEOM(y,t,pot):
"""
NAME:
linearEOM
PURPOSE:
the one-dimensional equation-of-motion
INPUT:
y - current phase-space position
t - current time
pot - (list of) linearPotential instance(s)
OUTPUT:
dy/dt
HISTORY:
2010-07-13 - Bovy (NYU)
"""
return [y[1],evaluatelinearForces(y[0],pot,t=t)]
def _ars_hpx_1d(x,args):
"""Internal function that evaluates h'(x) for ARS"""
pot,sigma2= args
return evaluatelinearForces(x,pot)/sigma2
def _ars_hpx_1d(x, args):
"""Internal function that evaluates h'(x) for ARS"""
pot, sigma2 = args
return evaluatelinearForces(x, pot) / sigma2