callable functions

    function psls_initialize(T, data, control, status)

Set default control values and initialize private data

Parameters:

data	holds private internal data
control	is a structure containing control information (see psls_control_type)
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are (currently): 0 The initialization was successful.

    function psls_read_specfile(T, control, specfile)

Read the content of a specification file, and assign values associated with given keywords to the corresponding control parameters. An in-depth discussion of specification files is available, and a detailed list of keywords with associated default values is provided in $GALAHAD/src/psls/PSLS.template. See also Table 2.1 in the Fortran documentation provided in $GALAHAD/doc/psls.pdf for a list of how these keywords relate to the components of the control structure.

Parameters:

control	is a structure containing control information (see psls_control_type)
specfile	is a one-dimensional array of type Vararg{Cchar} that must give the name of the specification file

    function psls_import(T, control, data, status, n, type, ne, row, col, ptr)

Import structural matrix data into internal storage prior to solution.

Parameters:

control	is a structure whose members provide control parameters for the remaining procedures (see psls_control_type)
data	holds private internal data
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are: 1 The import was successful, and the package is ready for the solve phase -1 An allocation error occurred. A message indicating the offending array is written on unit control.error, and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -2 A deallocation error occurred. A message indicating the offending array is written on unit control.error and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -3 The restriction n > 0 or requirement that type contains its relevant string ‘dense’, ‘coordinate’, ‘sparse_by_rows’ or ‘diagonal’ has been violated.
n	is a scalar variable of type Int32 that holds the number of rows in the symmetric matrix \(A\).
type	is a one-dimensional array of type Vararg{Cchar} that specifies the symmetric storage scheme used for the matrix \(A\). It should be one of ‘coordinate’, ‘sparse_by_rows’ or ‘dense’; lower or upper case variants are allowed.
ne	is a scalar variable of type Int32 that holds the number of entries in the lower triangular part of \(A\) in the sparse co-ordinate storage scheme. It need not be set for any of the other schemes.
row	is a one-dimensional array of size ne and type Int32 that holds the row indices of the lower triangular part of \(A\) in the sparse co-ordinate storage scheme. It need not be set for any of the other three schemes, and in this case can be C_NULL.
col	is a one-dimensional array of size ne and type Int32 that holds the column indices of the lower triangular part of \(A\) in either the sparse co-ordinate, or the sparse row-wise storage scheme. It need not be set when the dense storage scheme is used, and in this case can be C_NULL.
ptr	is a one-dimensional array of size n+1 and type Int32 that holds the starting position of each row of the lower triangular part of \(A\), as well as the total number of entries, in the sparse row-wise storage scheme. It need not be set when the other schemes are used, and in this case can be C_NULL.

    function psls_reset_control(T, control, data, status)

Reset control parameters after import if required.

Parameters:

control	is a structure whose members provide control parameters for the remaining procedures (see psls_control_type)
data	holds private internal data
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are: 1 The import was successful, and the package is ready for the solve phase

    function psls_form_preconditioner(T, data, status, ne, val)

Form and factorize a preconditioner \(P\) of the matrix \(A\).

Parameters:

data	holds private internal data
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are: 0 The factors were generated successfully. -1 An allocation error occurred. A message indicating the offending array is written on unit control.error, and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -2 A deallocation error occurred. A message indicating the offending array is written on unit control.error and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -26 The requested solver is not available. -29 This option is not available with this solver.
ne	is a scalar variable of type Int32 that holds the number of entries in the lower triangular part of the symmetric matrix \(A\).
val	is a one-dimensional array of size ne and type T that holds the values of the entries of the lower triangular part of the symmetric matrix \(A\) in any of the supported storage schemes.

    function psls_form_subset_preconditioner(T, data, status, ne, val, n_sub, sub)

Form and factorize a \(P\) preconditioner of a symmetric submatrix of the matrix \(A\).

Parameters:

data	holds private internal data
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are: 0 The factors were generated successfully. -1 An allocation error occurred. A message indicating the offending array is written on unit control.error, and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -2 A deallocation error occurred. A message indicating the offending array is written on unit control.error and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -26 The requested solver is not available. -29 This option is not available with this solver.
ne	is a scalar variable of type Int32 that holds the number of entries in the lower triangular part of the symmetric matrix \(A\).
val	is a one-dimensional array of size ne and type T that holds the values of the entries of the lower triangular part of the symmetric matrix \(A\) in any of the supported storage schemes.
n_sub	is a scalar variable of type Int32 that holds the number of rows (and columns) of the required submatrix of \(A\).
sub	is a one-dimensional array of size n_sub and type Int32 that holds the indices of the rows of required submatrix.

    function psls_update_preconditioner(T, data, status, ne, val, n_del, del)

Update the preconditioner \(P\) when rows (amd columns) are removed.

Parameters:

data	holds private internal data
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are: 0 The factors were generated successfully. -1 An allocation error occurred. A message indicating the offending array is written on unit control.error, and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -2 A deallocation error occurred. A message indicating the offending array is written on unit control.error and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -26 The requested solver is not available. -29 This option is not available with this solver.
ne	is a scalar variable of type Int32 that holds the number of entries in the lower triangular part of the symmetric matrix \(A\).
val	is a one-dimensional array of size ne and type T that holds the values of the entries of the lower triangular part of the symmetric matrix \(A\) in any of the supported storage schemes.
n_del	is a scalar variable of type Int32 that holds the number of rows (and columns) of (sub) matrix that are to be deleted.
del	is a one-dimensional array of size n_fix and type Int32 that holds the indices of the rows that are to be deleted.

    function psls_apply_preconditioner(T, data, status, n, sol)

Solve the linear system \(Px=b\).

Parameters:

data	holds private internal data
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are: 0 The required solution was obtained. -1 An allocation error occurred. A message indicating the offending array is written on unit control.error, and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively. -2 A deallocation error occurred. A message indicating the offending array is written on unit control.error and the returned allocation status and a string containing the name of the offending array are held in inform.alloc_status and inform.bad_alloc respectively.
n	is a scalar variable of type Int32 that holds the number of entries in the vectors \(b\) and \(x\).
sol	is a one-dimensional array of size n and type double. On entry, it must hold the vector \(b\). On a successful exit, its contains the solution \(x\). Any component corresponding to rows/columns not in the initial subset recorded by psls_form_subset_preconditioner, or in those subsequently deleted by psls_update_preconditioner, will not be altered.

    function psls_information(T, data, inform, status)

Provide output information

Parameters:

data	holds private internal data
inform	is a structure containing output information (see psls_inform_type)
status	is a scalar variable of type Int32 that gives the exit status from the package. Possible values are (currently): 0 The values were recorded successfully

    function psls_terminate(T, data, control, inform)

Deallocate all internal private storage

Parameters:

data	holds private internal data
control	is a structure containing control information (see psls_control_type)
inform	is a structure containing output information (see psls_inform_type)