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# ClpLsqr Class Reference

This class implements LSQR. More...

`#include <ClpLsqr.hpp>`

Collaboration diagram for ClpLsqr:

[legend]
List of all members.

## Public Member Functions
Constructors and destructors
| ClpLsqr ()
| Default constructor.
| ClpLsqr (ClpInterior *model)
| Constructor for use with Pdco model (note modified for pdco!!!!).
| ClpLsqr (const ClpLsqr &)
| Copy constructor.
ClpLsqr & | operator= (const ClpLsqr &rhs)
| Assignment operator. This copies the data.
| ~ClpLsqr ()
| Destructor.
Methods
bool | setParam (char *parmName, int parmValue)
| Set an int parameter.
void | do_lsqr (CoinDenseVector< double > &b, double damp, double atol, double btol, double conlim, int itnlim, bool show, Info info, CoinDenseVector< double > &x, int *istop, int *itn, Outfo *outfo, bool precon, CoinDenseVector< double > &Pr)
| Call the Lsqr algorithm.
void | matVecMult (int, CoinDenseVector< double > *, CoinDenseVector< double > *)
| Matrix-vector multiply - implemented by user.
void | matVecMult (int, CoinDenseVector< double > &, CoinDenseVector< double > &)
| Set an int parameter.
void | borrowDiag1 (double *array)
| diag1 - we just borrow as it is part of a CoinDenseVector<double>
## Public Attributes
Public member data
int | nrows_
| Row dimension of matrix.
int | ncols_
| Column dimension of matrix.
ClpInterior * | model_
| Pointer to Model object for this instance.
double * | diag1_
| Diagonal array 1.
double | diag2_
| Constant diagonal 2.

## Detailed Description

This class implements LSQR.

     LSQR solves  Ax = b  or  min ||b - Ax||_2  if damp = 0,
     or   min || (b)  -  (  A   )x ||   otherwise.
              || (0)     (damp I)  ||2
     A  is an m by n matrix defined by user provided routines
     matVecMult(mode, y, x)
     which performs the matrix-vector operations where y and x
     are references or pointers to CoinDenseVector objects.
     If mode = 1, matVecMult  must return  y = Ax   without altering x.
     If mode = 2, matVecMult  must return  y = A'x  without altering x.

    -----------------------------------------------------------------------
     LSQR uses an iterative (conjugate-gradient-like) method.
     For further information, see
     1. C. C. Paige and M. A. Saunders (1982a).
        LSQR: An algorithm for sparse linear equations and sparse least squares,
        ACM TOMS 8(1), 43-71.
     2. C. C. Paige and M. A. Saunders (1982b).
        Algorithm 583.  LSQR: Sparse linear equations and least squares problems,
        ACM TOMS 8(2), 195-209.
     3. M. A. Saunders (1995).  Solution of sparse rectangular systems using
        LSQR and CRAIG, BIT 35, 588-604.

     Input parameters:

     atol, btol  are stopping tolerances.  If both are 1.0e-9 (say),
                 the final residual norm should be accurate to about 9 digits.
                 (The final x will usually have fewer correct digits,
                 depending on cond(A) and the size of damp.)
     conlim      is also a stopping tolerance.  lsqr terminates if an estimate
                 of cond(A) exceeds conlim.  For compatible systems Ax = b,
                 conlim could be as large as 1.0e+12 (say).  For least-squares
                 problems, conlim should be less than 1.0e+8.
                 Maximum precision can be obtained by setting
                 atol = btol = conlim = zero, but the number of iterations
                 may then be excessive.
     itnlim      is an explicit limit on iterations (for safety).
     show = 1    gives an iteration log,
     show = 0    suppresses output.
     info        is a structure special to pdco.m, used to test if
                 was small enough, and continuing if necessary with smaller atol.

     Output parameters:
     x           is the final solution.
     *istop       gives the reason for termination.
     *istop       = 1 means x is an approximate solution to Ax = b.
                 = 2 means x approximately solves the least-squares problem.
     rnorm       = norm(r) if damp = 0, where r = b - Ax,
                 = sqrt( norm(r)**2  +  damp**2 * norm(x)**2 ) otherwise.
     xnorm       = norm(x).
     var         estimates diag( inv(A'A) ).  Omitted in this special version.
     outfo       is a structure special to pdco.m, returning information
                 about whether atol had to be reduced.

     Other potential output parameters:
     anorm, acond, arnorm, xnorm

Definition at line 73 of file ClpLsqr.hpp.

## Constructor & Destructor Documentation

ClpLsqr::ClpLsqr | ( |  | ) |

Default constructor.

ClpLsqr::ClpLsqr | ( | ClpInterior * | model | ) |

Constructor for use with Pdco model (note modified for pdco!!!!).

ClpLsqr::ClpLsqr | ( | const ClpLsqr & |  | ) |

Copy constructor.

ClpLsqr::~ClpLsqr | ( |  | ) |

Destructor.

## Member Function Documentation

ClpLsqr& ClpLsqr::operator= | ( | const ClpLsqr & | rhs | ) |

Assignment operator. This copies the data.

bool ClpLsqr::setParam | ( | char * | parmName,
|  | int | parmValue |
| ) |  |  |

Set an int parameter.

void ClpLsqr::do_lsqr | ( | CoinDenseVector< double > & | b,
|  | double | damp,
|  | double | atol,
|  | double | btol,
|  | double | conlim,
|  | int | itnlim,
|  | bool | show,
|  | Info | info,
|  | CoinDenseVector< double > & | x,
|  | int * | istop,
|  | int * | itn,
|  | Outfo * | outfo,
|  | bool | precon,
|  | CoinDenseVector< double > & | Pr |
| ) |  |  |

Call the Lsqr algorithm.

void ClpLsqr::matVecMult | ( | int | ,
|  | CoinDenseVector< double > * | ,
|  | CoinDenseVector< double > * |  |
| ) |  |  |

Matrix-vector multiply - implemented by user.

void ClpLsqr::matVecMult | ( | int | ,
|  | CoinDenseVector< double > & | ,
|  | CoinDenseVector< double > & |  |
| ) |  |  |

Set an int parameter.

void ClpLsqr::borrowDiag1 | ( | double * | array | ) | `[inline]`

diag1 - we just borrow as it is part of a CoinDenseVector<double>

Definition at line 122 of file ClpLsqr.hpp.

References diag1_.

## Member Data Documentation

int ClpLsqr::nrows_

Row dimension of matrix.

Definition at line 83 of file ClpLsqr.hpp.

int ClpLsqr::ncols_

Column dimension of matrix.

Definition at line 85 of file ClpLsqr.hpp.

ClpInterior* ClpLsqr::model_

Pointer to Model object for this instance.

Definition at line 87 of file ClpLsqr.hpp.

double* ClpLsqr::diag1_

Diagonal array 1.

Definition at line 89 of file ClpLsqr.hpp.

Referenced by borrowDiag1().

double ClpLsqr::diag2_

Constant diagonal 2.

Definition at line 91 of file ClpLsqr.hpp.

The documentation for this class was generated from the following file:

- /home/coin/SVN-release/Blis-0.91.0/Clp/src/ClpLsqr.hpp