Documentation from the file
polytrope/0.8/idl/lane_emden_root.pro
| Routine |
Name: lane_emden_root
Description:
Main IDL program that
solves the Lane-Emden equation numerically
using Runge Kutta techniques given the input of the polytropic
index from test_le1. The output is the arrays that are used in the
final polytrope structure.
Syntax:
lane_emden_root, x, xsi, y1, y2
Output:x:
x is an IDL floating_point and the value of the first root of the
Lane-Emden equation
xsi:
xsi is an IDL dblarr which is the
dimensionless distance variable in the Lane-Endem equation.
It is defined by xsi=r/a where "a"
is a unit of length suitable for a polytrope.
y1:
y1 is an IDL dblarr that
represents the scaled mass density.
y1 is defined as follows: mass density equals a constant lambda
times phi raised to the power n, where n is the polytropic index
in the range [0.,4.999999] and lambda is a scaling parameter identified
by the central desity of the star, thereby normalizing the function
phi to unity at the center
y2:
y2 is an IDL dblarr which is the derivative of y1 with respect to xsi.
|
-top-
|
