==========================
Conjugated Gradient Method                                               [TOC]
==========================

We show a simple generic implementation of the conjugated gradient (cg) method.
This implementation works for any symmetric matrix type that implement the
matrix-vector product.  In this example we use it for a *sparse symmetric
system matrix*.


Conjugated Gradient (cg) Method
===============================
The implementation only requires that the underlying BLAS routines are
available.  So if you want to play around with different matrix types make sure
that the corresponding __matrix-vector__ product is implemented.  Recall that
FLENS is doing the mapping of _overloaded operator notation_ to underlying
_BLAS call_ for you.  For your own matrix type just throw-in an appropriate
`blas::mv` function, that's it.

In __another example__ we will reuse this generic implementation for a simple
user-defined matrix type.

:import: flens/examples/cg.h [stripped, downloadable]


Example Code
============
:import: flens/examples/sycrs-cg.cc [stripped, downloadable]

Some Notes
==========
:import: flens/examples/sycrs-cg.cc [brief]


Compile
=======

  *--[SHELL]----------------------------------------------------------------*
  |                                                                         |
  |  cd flens/examples                                                      |
  |  g++ -Wall -std=c++11 -I../.. -o sycrs-cg sycrs-cg.cc                   |
  |                                                                         |
  *-------------------------------------------------------------------------*


Run
===

  *--[SHELL]----------------------------------------------------------------*
  |                                                                         |
  |  cd flens/examples                                                      |
  |  ./sycrs-cg                                                             |
  |                                                                         |
  *-------------------------------------------------------------------------*

:links: matrix-vector   -> doc:flens/blas/level2/mv#3
        another example -> doc:flens/examples/my-symatrix

:navigate: __up__    -> doc:flens/examples/tutorial
           __back__  -> doc:flens/examples/gecrs-superlu