DPRJIS is called to compute and process the matrix P = A - HEL(1)J, where J is an approximation to the Jacobian dr/dy, where r = g(t,y) - A(t,y)*s.
J is computed by columns, either by the user-supplied routine JAC if MITER = 1, or by finite differencing if MITER = 2.
J is stored in WK, rescaled, and ADDA is called to generate P.
The matrix P is subjected to LU decomposition in CDRV. P and its LU decomposition are stored separately in WK.
In addition to variables described previously, communication with DPRJIS uses the following:
array containing predicted values on entry.
work array of length N (ACOR in DSTODI).
array containing r evaluated at predicted y. On output it contains the residual evaluated at current values of t and y.
array containing predicted values of dy/dt (SAVF in DSTODI).
real work space for matrices. On output it contains P and its sparse LU decomposition. Storage of matrix elements starts at WK(3). WK also contains the following matrix-related data. WK(1) = SQRT(UROUND), used in numerical Jacobian increments.
integer work space for matrix-related data, assumed to be equivalenced to WK. In addition, WK(IPRSP) and IWK(IPISP) are assumed to have identical locations.
EL(1) (input).
output error flag (in COMMON). = 0 if no error. = 1 if zero pivot found in CDRV. = IRES (= 2 or 3) if RES returned IRES = 2 or 3. = -1 if insufficient storage for CDRV (should not occur). = -2 if other error found in CDRV (should not occur here).
output flag = 1 to indicate that the Jacobian matrix (or approximation) is now current.
This routine also uses other variables in global structures.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| integer, | dimension(*) | :: | Neq | |||
| real(kind=dp), | intent(inout), | dimension(*) | :: | Y | ||
| real(kind=dp), | intent(in), | dimension(Nyh,*) | :: | Yh | ||
| integer, | intent(in) | :: | Nyh | |||
| real(kind=dp), | intent(in), | dimension(*) | :: | Ewt | ||
| real(kind=dp), | intent(inout), | dimension(*) | :: | Rtem | ||
| real(kind=dp), | dimension(*) | :: | Savr | |||
| real(kind=dp), | dimension(*) | :: | S | |||
| real(kind=dp), | intent(inout), | dimension(*) | :: | Wk | ||
| integer, | dimension(*) | :: | Iwk | |||
| real | :: | res | ||||
| integer | :: | jac | ||||
| real | :: | adda |