* SUBROUTINE PF1F01                ALL SYSTEMS                97/12/01
C PORTABILITY : ALL SYSTEMS
C 97/12/01 LU : ORIGINAL VERSION
*
* PURPOSE :
* COMPUTATION OF THE VALUE AND THE GRADIENT OF THE OBJECTIVE FUNCTION.
*
* PARAMETERS:
*  II  NF  NUMBER OF VARIABLES.
*  RI  X(NF)  VECTOR OF VARIABLES.
*  RI  GF(NF)  GRADIENT OF THE MODEL FUNCTION.
*  RO  G(NF)  GRADIENT OF THE OBJECTIVE FUNCTION.
*  RI  FF  VALUE OF THE MODEL FUNCTION.
*  RO  F  VALUE OF THE OBJECTIVE FUNCTION.
*  II  KD  DEGREE OF REQUIRED DERIVATIVES.
*  II  LD  DEGREE OF PREVIOUSLY COMPUTED DERIVATIVES.
*  II  IEXT  TYPE OF EXTREMUM. IEXT=0-MINIMUM. IEXT=1-MAXIMUM.
*
* SUBPROGRAMS USED :
*  S   MXVCOP  COPYING OF A VECTOR.
*  S   MXVNEG  COPYING OF A VECTOR WITH CHANGE OF THE SIGN.
*
      SUBROUTINE PF1F01(NF,X,GF,G,FF,F,KD,LD,IEXT,POBJ,PDOBJ)
      DOUBLE PRECISION F,FF
      INTEGER          IEXT,KD,LD,NF
      DOUBLE PRECISION GF(*),G(*),X(*)
      INTEGER          NADD,NDEC,NFG,NFH,NFV,NIT,NREM,NRES
      EXTERNAL         POBJ,PDOBJ
      COMMON           /STAT/NRES,NDEC,NREM,NADD,NIT,NFV,NFG,NFH
      IF (KD.LE.LD) RETURN
      IF (LD.GE.0) GO TO 10
      NFV = NFV + 1
      CALL POBJ(NF,X,FF)
      IF (IEXT.LE.0) THEN
          F =  FF
      ELSE
          F = -FF
      END IF
   10 IF (KD.LT.1) GO TO 20
      IF (LD.GE.1) GO TO 20
      NFG = NFG + 1
      CALL PDOBJ(NF,X,GF)
      IF (IEXT.GT.0) THEN
          CALL MXVNEG(NF,GF,G)
      END IF
   20 LD = KD
      RETURN
      END