DAPPLY_POLY_GENR (job, p, a, ia, ja, nz, x, y, ndeg, n, iparam)
job integer*4 On entry, defines the operation to be performed: job = 0 : y = inverse(Q) * x job = 1 : y = inverse(transp(Q)) * x where Q is the polynomial preconditioner. On exit, job is unchanged. p real*8 On entry, a one-dimensional array of length at least 3*n that contains information for use by the polynomial preconditioner and workspace. On exit, the part of array P that contains the information related to the polynomial preconditioner is unchanged. The part used as workspace is overwritten. a real*8 On entry, a one-dimensional array of length at least nz containing the nonzero elements of the matrix A. On exit, a is unchanged. ia integer*4 On entry, a one-dimensional array of length at least n+1, containing the starting indices of each row in arrays JA and A. On exit, ia is unchanged. ja integer*4 On entry, a one-dimensional array of length at least nz, containing the column values of each nonzero element of the matrix A. On exit, ja is unchanged. nz integer*4 On entry, the number of nonzero elements stored in array A. On exit, nz is unchanged. x real*8 On entry, a one-dimensional array of length at least n, containing the elements of vector x, accessed with unit increment. On exit, x is unchanged. y real*8 On entry, a one-dimensional array of length at least n. On exit, array Y is overwritten by the output vector y. The elements of array Y are accessed with unit increment. ndeg integer*4 On entry, the degree of the polynomial in the polynomial preconditioner. On exit, ndeg is unchanged. n integer*4 On entry, the order of the matrix A. On exit, n is unchanged. iparam integer*4 On entry, a one-dimensional array of length at least 50. The variables in the IPARAM array are assigned the values listed in Table 10-4 of the CXML Reference Guide. Of the first 50 values, the 30th - 50th elements in IPARAM are reserved for the use of CXML.
DAPPLY_POLY_GENR applies the polynomial preconditioner for a sparse matrix stored using the general storage by rows scheme. The input vector, p, contains information for use by the routine. This vector is generated by a call to the routine DCREATE_POLY_GENR prior to a call to one of the iterative solvers with polynomial preconditioning. Depending on the value of the input parameter job, DAPPLY_POLY_GENR operates on either the preconditioning matrix or its transpose. This routine is available in both serial and parallel versions. The routine names and parameter list are identical for both versions. For information about linking to the serial or to the parallel library, refer to the CXML Reference Manual.