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*DECK MOCSCEL
SUBROUTINE MOCSCEL(N,NREG,NSOUT,M,NOM,NZON,H,SIGANG,DSIG,EXPT,
1 EXP2,NMU,ZMU)
*
*-----------------------------------------------------------------------
*
*Purpose:
* Calculate coefficients of a track for the cyclic characteristics
* integration: Linear-Discontinuous-Characteristics scheme with exact
* exponential and 'source term isolation' option turned off.
*
*Copyright:
* Copyright (C) 2015 Ecole Polytechnique de Montreal
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version
*
*Author(s): A. Hebert
*
*Parameters: input
* N number of elements in the current track.
* NREG number of volumes.
* NSOUT number of surfaces.
* M number of material mixtures.
* NOM vector containing the region number of the different segments
* of this track.
* NZON index-number of the mixture type assigned to each volume.
* H vector containing the lenght of the different segments of this
* track.
* SIGANG macroscopic total cross sections and albedos.
* NMU order of the polar quadrature set.
* ZMU inverse of polar quadrature cosines.
*
*Parameters: output
* DSIG macroscopic total cross sections.
* EXPT track coefficient.
* EXP2 quadratic expansion of (1-exp(-a*L))/L with small argument.
*
*-----------------------------------------------------------------------
*
IMPLICIT NONE
*----
* SUBROUTINE ARGUMENTS
*----
INTEGER N,NREG,NSOUT,M,NOM(N),NZON(-NSOUT:NREG),NMU
REAL SIGANG(-6:M),ZMU(NMU)
DOUBLE PRECISION H(N),DSIG(N),EXPT(NMU,N),EXP2(5,NMU,N)
*----
* LOCAL VARIABLES
*----
INTEGER I,NOMI,NUMOLD,NZI,IMU
DOUBLE PRECISION TAUDMIN,SQ3,HID,TAUD,TEMP,C1,C2,H2,H3
* tabulated exponential common block
PARAMETER ( TAUDMIN=2.0D-2 )
*
SQ3=SQRT(3.0D0)
NUMOLD=NOM(1)
DO I=1,N
NOMI=NOM(I)
NZI=NZON(NOMI)
DSIG(I)=SIGANG(NZI)
IF(NZI.LT.0) THEN
DO IMU=1,NMU
EXP2(2,IMU,I)=0.D0
EXP2(3,IMU,I)=0.D0
EXP2(5,IMU,I)=0.D0
ENDDO
IF(NUMOLD.NE.NOMI) THEN
DO IMU=1,NMU
EXP2(1,IMU,I)=SIGANG(NZI)
EXP2(4,IMU,I)=EXP2(1,IMU,I)
EXPT(IMU,I)=EXP2(1,IMU,I)
ENDDO
ELSE
DO IMU=1,NMU
EXP2(1,IMU,I)=1.D0
EXP2(4,IMU,I)=1.D0
EXPT(IMU,I)=EXP2(1,IMU,I)
ENDDO
ENDIF
ELSE
DO IMU=1,NMU
HID=DBLE(H(I)*ZMU(IMU))
TAUD=SIGANG(NZI)*HID
IF(TAUD.LE.TAUDMIN) THEN
* Use Taylor series expansions
H2=HID*HID
H3=H2*HID
EXPT(IMU,I)=TAUD*(0.5D0*TAUD-1.0D0)+1.0D0
EXP2(1,IMU,I)=HID*(TAUD*(TAUD/6.0D0-0.5D0)+1.0D0)
EXP2(2,IMU,I)=H2*(TAUD*(TAUD-4.0D0)+12.0D0)/24.0D0
EXP2(3,IMU,I)=-SQ3*H3*(TAUD*(TAUD-2.0D0)+4.0D0)/24.0D0
EXP2(4,IMU,I)=-SQ3*TAUD*(TAUD*(TAUD-2.0D0)+4.0D0)
1 /24.0D0
EXP2(5,IMU,I)=H3*(TAUD*TAUD-TAUD+4.0D0)/40.0D0
ELSE
* Use exact exponential
EXPT(IMU,I)=EXP(-TAUD)
TEMP=(1.D0-EXPT(IMU,I))/TAUD
EXP2(1,IMU,I)=TEMP*HID
EXP2(2,IMU,I)=HID*(1.D0-TEMP)/DSIG(I)
EXP2(3,IMU,I)=-SQ3*HID*(2.0D0-(TAUD+2.0D0)*TEMP)
1 /DSIG(I)**2
EXP2(4,IMU,I)=-SQ3*(2.0D0-(TAUD+2.0D0)*TEMP)/TAUD
C1=TAUD*(TAUD-6.0D0)-12.0D0
C2=TAUD*(3.0D0*TAUD+12.0D0)+12.0D0
EXP2(5,IMU,I)=(C1+C2*TEMP)/(TAUD*DSIG(I)**3)
ENDIF
ENDDO
ENDIF
NUMOLD=NOMI
ENDDO
*
RETURN
END
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