Module order_parameters

Module for the conversion of order parameters to specific model parameters and vice versa.

Functions

float iso_cone_theta_to_S(theta)
Convert the isotropic cone angle to the order parameter S.

float iso_cone_S_to_theta(S)
Convert the isotropic cone order parameter S into the cone angle.

Variables

__package__ = 'maths_fns'

Imports: acos, cos, pi, sqrt

Function Details

iso_cone_theta_to_S(theta)

Convert the isotropic cone angle to the order parameter S.

This uses Woessner's diffusion in a cone order parameter defined as:

   S = 1/2 (1 + cos(theta)) * cos(theta)

Parameters:

• theta (float) - The isotropic cone angle.

Returns: float

The order parameter value.

iso_cone_S_to_theta(S)

Convert the isotropic cone order parameter S into the cone angle.

This uses Woessner's diffusion in a cone order parameter defined as:

   S = 1/2 (1 + cos(theta)) * cos(theta)

The conversion equation is:

   theta = acos((sqrt(8.0*S + 1) - 1)/2)

Hence the cone angle is only between 0 and 2pi/3, as the order parameter for higher cone angles is ambiguous.

Parameters:

• S (float) - The order parameter value (not squared).

Returns: float

The value of cos(theta).