#include <string>
#include <iostream>
#include <iomanip>

#include "TRandom3.h"
#include "TMatrixTSym.h"

#include "JLang/JException.hh"
#include "JMath/JMatrixNS.hh"
#include "JMath/JMathTestkit.hh"

#include "Jeep/JTimer.hh"
#include "Jeep/JParser.hh"
#include "Jeep/JMessage.hh"


/**
 * \file
 *
 * Example program to test inversion of symmetric matrix.
 * \author mdejong
 */
int main(int argc, char**argv)
{
  using namespace std;
  using namespace JPP;

  int       N;
  double    precision;
  size_t    numberOfInversions;
  UInt_t    seed;
  int       debug;

  try {

    JParser<> zap("Example program to test inversion of symmetric matrix.");

    zap['N'] = make_field(N);
    zap['e'] = make_field(precision)          = 1.0e-6;
    zap['n'] = make_field(numberOfInversions) = 1;
    zap['S'] = make_field(seed)               = 0;
    zap['d'] = make_field(debug)              = 3;

    zap(argc, argv);
  }
  catch(const exception &error) {
    FATAL(error.what() << endl);
  }

  
  gRandom->SetSeed(seed);

  const Double_t xmin = -1.0;
  const Double_t xmax = +1.0;
 
  JMatrixNS A(N);

  for (int i = 0; i != N; ++i) {

    A(i,i) = gRandom->Uniform(xmin,xmax); 

    for (int j = 0; j != i; ++j) {
      A(j,i) = A(i,j) = gRandom->Uniform(xmin,xmax); 
    }
  }


  try {

    DEBUG("Matrix A" << endl);
    DEBUG(A << endl);
 
    JMatrixNS B(A);

    JTimer timer;

    timer.start();

    for (size_t i = 2*(numberOfInversions/2) + 1; i != 0; --i) {
      B.invert();
    }

    timer.stop();

    NOTICE("Elapsed time (Jpp)  [us] " << setw(8) << timer.usec_wall << endl);
    DEBUG("Matrix A^-1" << endl);
    DEBUG(B << endl);

    {
      TMatrixTSym<double> R(B.size());

      for (size_t row = 0; row != B.size(); ++row) {
	for (size_t col = 0; col != B.size(); ++col) {
	  R(row, col) = B(row, col);
	}
      }

      timer.start();

      for (size_t i = 2*(numberOfInversions/2) + 1; i != 0; --i) {
	R.InvertFast();
      }

      timer.stop();

      NOTICE("Elapsed time (ROOT) [us] " << setw(8) << timer.usec_wall << endl);
    }

    JMatrixNS C(A);

    C.mul(B);
    
    DEBUG("Matrix A x A^-1" << endl);
    DEBUG(C << endl);
    
    NOTICE("A x A^-1 = I ? "                     << C.isIdentity(precision)                 << endl);
    
    if (!C.isIdentity(precision)) {
      ERROR("Matrix A x A^-1 /= I" << endl);
    }

    ASSERT (C.isIdentity(precision));

    const double big = 1.0e5;

    for (int i = 0; i != N; ++i) {

      A(i,i) += big;
 
      timer.reset();
      timer.start();

      B.update(i, big);

      timer.stop();

      NOTICE("Elapsed time [us] " << setw(8) << timer.usec_wall << endl);
      NOTICE("Pivot " << setw(2) << i << '+' << big << ' ' << (JMatrixNS(A).mul(B).isIdentity(precision) ? "okay" : "error") << endl);

      ASSERT(JMatrixNS(A).mul(B).isIdentity(precision));

      A(i,i) -= big;

      B.update(i, -big);
    }

  }
  catch (const JException& error) {
    FATAL(error << endl);
  }

  return 0;
}