macro Inel_Flat_Plate_V2(alpha, alpha_v, sd, sd_v)
	' Version by Matthew Rowles CSIRO Minerals
	' Equations for correction of intensity and sample displacement for flat plate samples
	' in fixed incident beam geometry e.g. when using the Inel CPS120 position sensitive detector
	' Intensity correction derived from Toraya et al. (1993)
	' Sample displacement model derived by Ian Madsen
	' 2Theta = (alpha + beta)
	'   where beta  = angle between diffracted beam(s) and sample surface
	' Rs = 250mm for the Inel CPS120 detector - Rs must be defined in the input file
{
   #m_argu alpha    ' alpha = angle between incident beam and sample surface
   #m_argu sd       ' sd = displacement of the sample (in same units as detector radius)
	If_Prm_Eqn_Rpt(alpha, alpha_v, min 0.0001 max 90)
   If_Prm_Eqn_Rpt(sd, sd_v, min -1 max 1)
 
	scale_pks = 
		IF (2 Th) < CeV(alpha, alpha_v) Deg THEN 
			0                                 
		ELSE
			2 / (1 + (Sin(CeV(alpha, alpha_v) Deg) / Sin(2 Th - CeV(alpha, alpha_v) Deg)))
		ENDIF;
 
	th2_offset = 
		IF CeV(sd, sd_v) == 0 THEN 
			0
		ELSE
			- Rad (CeV(sd, sd_v) Sin(2 Th)) / (Rs Sin(CeV(alpha, alpha_v) Deg))
		ENDIF;
}