/*****************************************************************************
*
* McStas, neutron ray-tracing package
*         Copyright 1997-2024, All rights reserved
*         Technical University of Denmark, Kongens Lyngby, Denmark
*         Institut Laue Langevin, Grenoble, France
*
* Component: Spin_random
*
* %I
* Written by: Michael Schneider (SNAG)
* Date: 2024
* Origin: SNAG
*
* Set a random polarisation
*
* %D
*
* This component has no physical size or extent, it simply asigns the neutron
* ray polarisation randomly to either spin-up or spin-down.
*
* %P
* INPUT PARAMETERS:
*
* CALCULATED PARAMETERS:
*
* %E
*******************************************************************************/
DEFINE COMPONENT Spin_random

SETTING PARAMETERS ()
/* STATE PARAMETERS (x,y,z,vx,vy,vz,t,s1,s2,p) */
/* POLARISATION PARAMETERS (sx,sy,sz) */
TRACE
%{
  int S_check;
  sx = 0.0;
  sz = 0.0;
  do {
    sy = randpm1 ();
    S_check = 0;
    if (sy < 0) {
      sy = -1.0;
      S_check = 1;
    }
    if (sy > 0) {
      sy = 1.0;
      S_check = 1;
    }
  } while (S_check == 0);
%}

END