share/hompack/fortran/rhojac.f

   1       SUBROUTINE RHOJAC(A,LAMBDA,X,V,K,PAR,IPAR)
   2       DOUBLE PRECISION A(*),LAMBDA,X(*),V(*),PAR(*)
   3       INTEGER IPAR(*),K
   4 C
   5 C PAR(1:*) AND IPAR(1:*) ARE ARRAYS FOR (OPTIONAL) USER PARAMETERS,
   6 C    WHICH ARE SIMPLY PASSED THROUGH TO THE USER WRITTEN SUBROUTINES
   7 C    RHO, RHOJAC.
   8 C
   9 C RETURN IN THE VECTOR  V  THE KTH COLUMN OF THE JACOBIAN
  10 C MATRIX [D RHO/D LAMBDA, D RHO/DX] EVALUATED AT THE POINT
  11 C (A, LAMBDA, X).
  12 C
  13 C THE FOLLOWING CODE IS SPECIFICALLY FOR THE POLYNOMIAL SYSTEM DRIVER
  14 C  POLSYS , AND SHOULD BE USED VERBATUM WITH  POLSYS .  IF THE USER IS
  15 C CALLING  FIXP??  OR   STEP??  DIRECTLY, HE MUST SUPPLY APPROPRIATE
  16 C REPLACEMENT CODE HERE.
  17       INTEGER J,N,N2
  18       N=IPAR(1)
  19       N2=2*N
  20       IF (K .EQ. 1) THEN
  21 C FORCE PREDICTED POINT TO HAVE  LAMBDA .GE. 0  .
  22         IF (LAMBDA .LT. 0.0) LAMBDA=0.0
  23         CALL HFUNP(A,LAMBDA,X,PAR,IPAR)
  24         DO 10 J=1,N2
  25           V(J)=PAR(IPAR(3 + (6-1)) + (J-1))
  26    10   CONTINUE
  27         RETURN
  28       ELSE
  29         DO 20 J=1,N2
  30           V(J)=PAR(IPAR(3 + (5-1)) + (J-1) + N2*(K-2))
  31    20   CONTINUE
  32       ENDIF
  33 C
  34       RETURN
  35       END