The routine may be called by the names f11jpf or nagf_sparse_complex_herm_precon_ilu_solve.
f11jpf solves a system of linear equations
involving the preconditioning matrix , corresponding to an incomplete Cholesky decomposition of a complex sparse Hermitian matrix stored in symmetric coordinate storage (SCS) format (see Section 2.1.2 in the F11 Chapter Introduction), as generated by f11jnf.
In the above decomposition is a complex lower triangular sparse matrix with unit diagonal, is a real diagonal matrix and is a permutation matrix. and are supplied to f11jpf through the matrix
which is a lower triangular complex sparse matrix, stored in SCS format, as returned by f11jnf. The permutation matrix is returned from f11jnf via the array ipiv.
f11jpf may also be used in combination with f11jnf to solve a sparse complex Hermitian positive definite system of linear equations directly (see f11jnf).
1: – IntegerInput
On entry: , the order of the matrix . This must be the same value as was supplied in the preceding call to f11jnf.
2: – Complex (Kind=nag_wp) arrayInput
On entry: the values returned in the array a by a previous call to f11jnf.
3: – IntegerInput
On entry: the dimension of the arrays a, irow and icol as declared in the (sub)program from which f11jpf is called. This must be the same value supplied in the preceding call to f11jnf.
On entry: ifail must be set to , or to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of means that an error message is printed while a value of means that it is not.
If halting is not appropriate, the value or is recommended. If message printing is undesirable, then the value is recommended. Otherwise, the value is recommended. When the value or is used it is essential to test the value of ifail on exit.
On exit: unless the routine detects an error or a warning has been flagged (see Section 6).
6Error Indicators and Warnings
If on entry or , explanatory error messages are output on the current error message unit (as defined by x04aaf).