*
* $Id$
*
* $Log$
* Revision 1.1  2000/06/19 20:00:34  eugenio
* Initial revision
*
* Revision 1.1.1.1  1994/10/08  02:21:28  zfiles
* first version of qqlib in CVS
*
*
#include "sys/CLEO_machine.h"
#include "pilot.h"
*CMZ :  1.03/14 03/07/91  15.23.53  by  Peter C Kim
*CMZ :  1.01/00 17/09/90  23.22.38  by  Paul Avery
*CMZ :  1.00/00 04/06/90  18.55.44  by  Jorge L. Rodriguez
*-- Author :

      SUBROUTINE EVGENH(FUNCTN,X00,X11,ANSWER)

      IMPLICIT DOUBLE PRECISION(A-H,K,O-Z)
      REAL RANP
      EXTERNAL RANP
      DOUBLE PRECISION FUNCTN
      EXTERNAL FUNCTN

      DATA EPS1/1.D-6/
      DATA EPS2/1.D-4/
      F(X)=SGNN*FUNCTN(X)
      SGNN=+1.D0
      X0=DMIN1(X00,X11)
      X1=DMAX1(X00,X11)
      DIFF=1.D00
      EPS=EPS1
      DEL0=DABS(X1-X0)*1.D-6
      DEL1=0.1*DEL0
      F0=F(X0)
      Y0=X0
      F1=F(X1)
      Y1=X1
      IF(F0 .LE. F1)GOTO 10021
      F0=-F0
      F1=-F1
      SGNN=-1.D0
10021 CONTINUE
      DEL000=F1-F0
      VAL=DEL000*RANP(0)+F0
      J=0
10030 M=1
      GOTO 10033
10031 M=M+1
10033 IF((M).GT.(6))GOTO 10032
      JJ=J
10040 DO 10041 I=1,6
      AAA0=ANSWER
      ANSWER=0.5D0*(Y1+Y0)
      FM=F(ANSWER)
      IF(FM.EQ.VAL) GOTO 10050
      IF(FM .GE. VAL)GOTO 10071
      Y0=ANSWER
      F0=FM
      GOTO 10081
10071 CONTINUE
      Y1=ANSWER
      F1=FM
10081 CONTINUE
10061 CONTINUE
10041 CONTINUE
10042 CONTINUE
      DIFF=ANSWER-AAA0
      ANSWER=0.5D0*(Y1+Y0)
10090 J=JJ+1
      GOTO 10093
10091 J=J+1
10093 IF((J).GT.(7))GOTO 10092
      FM=F(ANSWER)
      ERROLD=ERROR
      ERROR=DABS(VAL-FM)/DEL000
      IF (ERROR.LE.EPS) GOTO 10050
      IF(ERROR.GT.ERROLD.AND.J.GT.3)GOTO 10092
      DELTA=DMIN1(DEL0,DABS(DIFF))
      ANO=ANSWER
      ANN=ANO+DELTA
      IF(ANN .LE. X1)GOTO 10111
      EPS=EPS2
      DELTA=0.5*DELTA
      ANN=X1
      FM=F(ANN-DELTA)
10111 CONTINUE
      FM1=(F(ANN)-FM)/DELTA
      IF(FM1 .NE. 0.D0)GOTO 10131
      ANSWER=ANO
      GOTO 10092
10131 CONTINUE
      DIFF=(FM-VAL)/FM1
      ANSWER=ANO-DIFF
      IF((ANSWER .GE. Y0) .AND. (ANSWER .LE. Y1))GOTO 10151
      ANSWER=ANO
      GOTO 10092
10151 CONTINUE
      IF (DABS(DIFF).LT.DEL1) GOTO 10050
      GOTO 10091
10092 CONTINUE
      GOTO 10031
10032 CONTINUE
10050 CONTINUE
      RETURN
      END