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*DECK MOCSCAS
SUBROUTINE MOCSCAS(N,NREG,NSOUT,M,NOM,NZON,H,SIGANG,EXPT,EXP2,
1 NMU,ZMU)
*
*-----------------------------------------------------------------------
*
*Purpose:
* Calculate coefficients of a track for the cyclic characteristics
* integration: Step-Characteristics scheme with tabulated exponential
* and 'source term isolation' option turned off.
*
*Copyright:
* Copyright (C) 2002 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): R. Roy and R. Le Tellier
*
*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
* 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),EXPT(NMU,N),EXP2(2,NMU,N)
*----
* LOCAL VARIABLES
*----
INTEGER I,NOMI,NUMOLD,NZI,IMU
REAL TAU
DOUBLE PRECISION TAUDMIN,HID,TAUD,TEMP,HID2,TAUD3,TAUD4,TAUD5
* tabulated exponential common block
REAL E0, E1, PAS1, DX1, XLIM1
INTEGER MEX1, LAU
PARAMETER ( MEX1=7936, TAUDMIN=2.D-2 )
COMMON /EXP1/ E0(0:MEX1),E1(0:MEX1),PAS1,DX1,XLIM1
*
NUMOLD=NOM(1)
DO I=1,N
NOMI=NOM(I)
NZI=NZON(NOMI)
IF(NZI.LT.0) THEN
IF(NUMOLD.NE.NOMI) THEN
DO IMU=1,NMU
EXP2(1,IMU,I)=SIGANG(NZI)
EXPT(IMU,I)=EXP2(1,IMU,I)
ENDDO
ELSE
DO IMU=1,NMU
EXP2(1,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
TAU=REAL(TAUD)
IF(TAU.GE.XLIM1) THEN
* Out of the table range
EXPT(IMU,I)=0.D0
TEMP=1.D0/TAUD
EXP2(1,IMU,I)=TEMP*HID
EXP2(2,IMU,I)=HID*(1.D0-TEMP)/DBLE(SIGANG(NZI))
ELSE
* Linear interpolation in table of (1-exp(-x))/x
LAU=INT(TAU*PAS1)
TEMP=DBLE(E0(LAU)+E1(LAU)*TAU)
EXPT(IMU,I)=1.D0-TEMP*TAUD
EXP2(1,IMU,I)=TEMP*HID
IF(TAUD.LE.TAUDMIN) THEN
* and expansion in Taylor serie in O(TAUD^3)
TAUD3=TAUD/3.D0
TAUD4=0.125D0*TAUD
TAUD5=0.2D0*TAUD
HID2=HID*HID
EXP2(2,IMU,I)=HID2*(0.5D0-TAUD3*(0.5D0-TAUD4
1 *(1.D0-TAUD5)))
ELSE
EXP2(2,IMU,I)=HID*(1.D0-TEMP)/DBLE(SIGANG(NZI))
ENDIF
ENDIF
ENDDO
ENDIF
NUMOLD=NOMI
ENDDO
*
RETURN
END
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