C MARCH 3, 2001; MARCH 24, 2005
C FUNCTION DECLARATIONS FOR THE COST FUNCTION OF A GENERALIZED
C NETWORK FLOW PROBLEM.  THE FUNCTIONS C(I,F), DC(I,F), DCINV(I,F)
C GIVE THE FUNCTION VALUE, DERIVATIVE VALUE, DERIVATIVE INVERSE VALUE
C FOR A 
C          QUADRATIC COST FUNCTION 
C FOR ARC I WITH FLOW F.
C THE FUNCTION PARAMETERS A(I), CDAT(I,1) ARE SPECIFIED IN THE
C ASCII FILE   NL013.DAT
C A(I) IS THE LINEAR COST COEFFICIENT.  CDAT(I,1) IS THE QUADRATIC
C COST COEFFICIENT.  CDAT(I,1)=0.0 INDICATES A LINEAR COST ARC.

      FUNCTION C(I,F)
      IMPLICIT NONE
      INTEGER*4 MAXARCS,MAXNDAT,I
      PARAMETER (MAXARCS=20000, MAXNDAT=5)
      REAL*8 A(MAXARCS),CDAT(MAXARCS,MAXNDAT),F,C
      COMMON /LCOS/A
      COMMON /QCO1/CDAT
  
      C=CDAT(I,1)*F*F+A(I)*F
      RETURN
      END
      
      FUNCTION DC(I,F)
      IMPLICIT NONE
      INTEGER*4 MAXARCS,MAXNDAT,I
      PARAMETER (MAXARCS=20000, MAXNDAT=5)
      REAL*8 A(MAXARCS),CDAT(MAXARCS,MAXNDAT),F,DC
      COMMON /LCOS/A
      COMMON /QCO1/CDAT
  
      DC=2.0*CDAT(I,1)*F+A(I)
      RETURN
      END
      
      FUNCTION DCINV(I,T)
      IMPLICIT NONE
      INTEGER*4 MAXARCS,MAXNDAT,I
      PARAMETER (MAXARCS=20000, MAXNDAT=5)
      REAL*8 A(MAXARCS),CDAT(MAXARCS,MAXNDAT),T,DCINV
      COMMON /LCOS/A
      COMMON /QCO1/CDAT
  
      DCINV=(T-A(I))/(2.0*CDAT(I,1))
      RETURN
      END