*DECK DFDJC3 SUBROUTINE DFDJC3 (FCN, M, N, X, FVEC, FJAC, LDFJAC, IFLAG, + EPSFCN, WA) C***BEGIN PROLOGUE DFDJC3 C***SUBSIDIARY C***PURPOSE Subsidiary to DNLS1 and DNLS1E C***LIBRARY SLATEC C***TYPE DOUBLE PRECISION (FDJAC3-S, DFDJC3-D) C***AUTHOR (UNKNOWN) C***DESCRIPTION C C **** Double Precision version of FDJAC3 **** C C This subroutine computes a forward-difference approximation C to the M by N Jacobian matrix associated with a specified C problem of M functions in N variables. C C The subroutine statement is C C SUBROUTINE DFDJC3(FCN,M,N,X,FVEC,FJAC,LDFJAC,IFLAG,EPSFCN,WA) C C where C C FCN is the name of the user-supplied subroutine which C calculates the functions. FCN must be declared C in an external statement in the user calling C program, and should be written as follows. C C SUBROUTINE FCN(IFLAG,M,N,X,FVEC,FJAC,LDFJAC) C INTEGER LDFJAC,M,N,IFLAG C DOUBLE PRECISION X(N),FVEC(M),FJAC(LDFJAC,N) C ---------- C When IFLAG.EQ.1 calculate the functions at X and C return this vector in FVEC. C ---------- C RETURN C END C C The value of IFLAG should not be changed by FCN unless C the user wants to terminate execution of DFDJC3. C In this case set IFLAG to a negative integer. C C M is a positive integer input variable set to the number C of functions. C C N is a positive integer input variable set to the number C of variables. N must not exceed M. C C X is an input array of length N. C C FVEC is an input array of length M which must contain the C functions evaluated at X. C C FJAC is an output M by N array which contains the C approximation to the Jacobian matrix evaluated at X. C C LDFJAC is a positive integer input variable not less than M C which specifies the leading dimension of the array FJAC. C C IFLAG is an integer variable which can be used to terminate C THE EXECUTION OF DFDJC3. See description of FCN. C C EPSFCN is an input variable used in determining a suitable C step length for the forward-difference approximation. This C approximation assumes that the relative errors in the C functions are of the order of EPSFCN. If EPSFCN is less C than the machine precision, it is assumed that the relative C errors in the functions are of the order of the machine C precision. C C WA is a work array of length M. C C***SEE ALSO DNLS1, DNLS1E C***ROUTINES CALLED D1MACH C***REVISION HISTORY (YYMMDD) C 800301 DATE WRITTEN C 890531 Changed all specific intrinsics to generic. (WRB) C 890831 Modified array declarations. (WRB) C 891214 Prologue converted to Version 4.0 format. (BAB) C 900326 Removed duplicate information from DESCRIPTION section. C (WRB) C 900328 Added TYPE section. (WRB) C***END PROLOGUE DFDJC3