callable functions

    function l2rt_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 l2rt_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 l2rt_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/l2rt/L2RT.template. See also Table 2.1 in the Fortran documentation provided in $GALAHAD/doc/l2rt.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 l2rt_control_type)
specfile	is a one-dimensional array of type Vararg{Cchar} that must give the name of the specification file

    function l2rt_import_control(T, control, data, status)

Import control parameters prior to solution.

Parameters:

control	is a structure whose members provide control parameters for the remaining procedures (see l2rt_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 (currently): 1 The import was successful, and the package is ready for the solve phase

    function l2rt_solve_problem(T, data, status, m, n, power, weight, shift,
                                x, u, v)

Solve the regularized-least-squares problem using reverse communication.

Parameters:

data	holds private internal data
status	is a scalar variable of type Int32 that gives the entry and exit status from the package. This must be set to 1 on initial entry. Set the argument u (below) to \(b\) for this entry. Possible exit values are: 0 the solution has been found 2 The user must perform the operation \[u := u + Av,\] and recall the function. The vectors \(u\) and \(v\) are available in the arrays u and v (below) respectively, and the result \(u\) must overwrite the content of u. No argument except u should be altered before recalling the function 3 The user must perform the operation \[v := v + A^Tu,\] and recall the function. The vectors \(u\) and \(v\) are available in the arrays u and v respectively, and the result \(v\) must overwrite the content of v. No argument except v should be altered before recalling the function 4 The user must reset u to \(b\) are recall the function. No argument except u should be altered before recalling the function -1 an array allocation has failed -2 an array deallocation has failed -3 one or more of n, m, weight or shift violates allowed bounds -18 the iteration limit has been exceeded -25 status is negative on entry
m	is a scalar variable of type Int32 that holds the number of equations (i.e., rows of \(A\)), \(m > 0\)
n	is a scalar variable of type Int32 that holds the number of variables (i.e., columns of \(A\)), \(n > 0\)
power	is a scalar of type T that holds the regularization power, \(p \geq 2\)
weight	is a scalar of type T that holds the regularization weight, \(\sigma > 0\)
shift	is a scalar of type T that holds the shift, \(\mu\)
x	is a one-dimensional array of size n and type T that holds the solution \(x\). The j-th component of x, j = 1, … , n, contains \(x_j\).
u	is a one-dimensional array of size m and type T that should be used and reset appropriately when status = 1 to 5 as directed by status.
v	is a one-dimensional array of size n and type T that should be used and reset appropriately when status = 1 to 5 as directed by status.

    function l2rt_information(T, data, inform, status)

Provides output information

Parameters:

data	holds private internal data
inform	is a structure containing output information (see l2rt_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 l2rt_terminate(T, data, control, inform)

Deallocate all internal private storage

Parameters:

data	holds private internal data
control	is a structure containing control information (see l2rt_control_type)
inform	is a structure containing output information (see l2rt_inform_type)