pythiaeRHIC/pythia/pyrnm3.f

0001
0002 C*********************************************************************
0003
0004 C...PYRNM3
0005 C...Calculates the running of M3, the SU(3) gluino mass parameter.
0006
0007       FUNCTION PYRNM3(RGUT)
0008
0009 C...Double precision and integer declarations.
0010       IMPLICIT DOUBLE PRECISION(A-H, O-Z)
0011       IMPLICIT INTEGER(I-N)
0012       INTEGER PYK,PYCHGE,PYCOMP
0013
0014 C...Local variables.
0015       DOUBLE PRECISION R
0016       DOUBLE PRECISION TOL
0017       EXTERNAL PYALPS
0018       DOUBLE PRECISION PYALPS
0019       DATA TOL/0.001D0/
0020       DATA R/0.61803399D0/
0021
0022       C=1D0-R
0023
0024       BX=RGUT*PYALPS(RGUT**2)
0025       AX=MIN(50D0,BX*0.5D0)
0026       CX=MAX(2000D0,2D0*BX)
0027
0028       X0=AX
0029       X3=CX
0030       IF(ABS(CX-BX).GT.ABS(BX-AX))THEN
0031         X1=BX
0032         X2=BX+C*(CX-BX)
0033       ELSE
0034         X2=BX
0035         X1=BX-C*(BX-AX)
0036       ENDIF
0037       AS1=PYALPS(X1**2)
0038       F1=ABS(X1-RGUT*AS1)
0039       AS2=PYALPS(X2**2)
0040       F2=ABS(X2-RGUT*AS2)
0041   100 IF(ABS(X3-X0).GT.TOL*(ABS(X1)+ABS(X2))) THEN
0042         IF(F2.LT.F1) THEN
0043           X0=X1
0044           X1=X2
0045           X2=R*X1+C*X3
0046           F1=F2
0047           AS2=PYALPS(X2**2)
0048           F2=ABS(X2-RGUT*AS2)
0049         ELSE
0050           X3=X2
0051           X2=X1
0052           X1=R*X2+C*X0
0053           F2=F1
0054           AS1=PYALPS(X1**2)
0055           F1=ABS(X1-RGUT*AS1)
0056         ENDIF
0057         GOTO 100
0058       ENDIF
0059       IF(F1.LT.F2) THEN
0060         PYRNM3=X1
0061         XMIN=X1
0062       ELSE
0063         PYRNM3=X2
0064         XMIN=X2
0065       ENDIF
0066
0067       RETURN
0068       END