# include <cmath>
# include <cstdlib>
# include <iostream>
# include <ctime>

using namespace std;

# include "cosine_transform.hpp"

//****************************************************************************80

double *r8vec_uniform_01_new ( int n, int &seed )

//****************************************************************************80
//
//  Purpose:
//
//    R8VEC_UNIFORM_01_NEW returns a new unit pseudorandom R8VEC.
//
//  Discussion:
//
//    This routine implements the recursion
//
//      seed = ( 16807 * seed ) mod ( 2^31 - 1 )
//      u = seed / ( 2^31 - 1 )
//
//    The integer arithmetic never requires more than 32 bits,
//    including a sign bit.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    19 August 2004
//
//  Author:
//
//    John Burkardt
//
//  Reference:
//
//    Paul Bratley, Bennett Fox, Linus Schrage,
//    A Guide to Simulation,
//    Second Edition,
//    Springer, 1987,
//    ISBN: 0387964673,
//    LC: QA76.9.C65.B73.
//
//    Bennett Fox,
//    Algorithm 647:
//    Implementation and Relative Efficiency of Quasirandom
//    Sequence Generators,
//    ACM Transactions on Mathematical Software,
//    Volume 12, Number 4, December 1986, pages 362-376.
//
//    Pierre L'Ecuyer,
//    Random Number Generation,
//    in Handbook of Simulation,
//    edited by Jerry Banks,
//    Wiley, 1998,
//    ISBN: 0471134031,
//    LC: T57.62.H37.
//
//    Peter Lewis, Allen Goodman, James Miller,
//    A Pseudo-Random Number Generator for the System/360,
//    IBM Systems Journal,
//    Volume 8, Number 2, 1969, pages 136-143.
//
//  Parameters:
//
//    Input, int N, the number of entries in the vector.
//
//    Input/output, int &SEED, a seed for the random number generator.
//
//    Output, double R8VEC_UNIFORM_01_NEW[N], the vector of pseudorandom values.
//
{
  int i;
  const int i4_huge = 2147483647;
  int k;
  double *r;

  if ( seed == 0 )
  {
    cerr << "\n";
    cerr << "R8VEC_UNIFORM_01_NEW - Fatal error!\n";
    cerr << "  Input value of SEED = 0.\n";
    exit ( 1 );
  }

  r = new double[n];

  for ( i = 0; i < n; i++ )
  {
    k = seed / 127773;

    seed = 16807 * ( seed - k * 127773 ) - k * 2836;

    if ( seed < 0 )
    {
      seed = seed + i4_huge;
    }

    r[i] = ( double ) ( seed ) * 4.656612875E-10;
  }

  return r;
}
//****************************************************************************80

double *cosine_transform_data ( int n, double d[] )

//****************************************************************************80
//
//  Purpose:
//
//    COSINE_TRANSFORM_DATA does a cosine transform on a vector of data.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    27 August 2015
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, integer N, the number of data points.
//
//    Input, double D[N], the vector of data.
//
//    Output, double COSINE_TRANSFORM_DATA[N], the transform coefficients.
//
{
  double angle;
  double *c;
  int i;
  int j;
  const double r8_pi = 3.141592653589793;

  c = new double[n];

  for ( i = 0; i < n; i++ )
  {
    c[i] = 0.0;
    for ( j = 0; j < n; j++ )
    {
      angle = r8_pi * ( double ) ( i * ( 2 * j + 1 ) ) / ( double ) ( 2 * n );
      c[i] = c[i] + cos ( angle ) * d[j];
    }
    c[i] = c[i] * sqrt ( 2.0 / ( double ) ( n ) );
  }
  return c;
}
//****************************************************************************80

double *cosine_transform_inverse ( int n, double c[] )

//****************************************************************************80
//
//  Purpose:
//
//    COSINE_TRANSFORM_INVERSE does an inverse cosine transform.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    27 August 2015
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, integer N, the number of data points.
//
//    Input, double C[N], the vector of transform coefficients
//
//    Output, double COSINE_TRANSFORM_INVERSE[N], the original data.
//
{
  double angle;
  double *d;
  int i;
  int j;
  double r8_pi = 3.141592653589793;

  d = new double[n];

  for ( i = 0; i < n; i++ )
  {
    d[i] = c[0] / 2.0;
    for ( j = 1; j < n; j++ )
    {
      angle = r8_pi * ( double ) ( ( 2 * i + 1 ) * j ) / ( double ) ( 2 * n );
      d[i] = d[i] + cos ( angle ) * c[j];
    }
    d[i] = d[i] * sqrt ( 2.0 / ( double ) ( n ) );
  }
  return d;
}
//****************************************************************************80

void timestamp ( )

//****************************************************************************80
//
//  Purpose:
//
//    TIMESTAMP prints the current YMDHMS date as a time stamp.
//
//  Example:
//
//    31 May 2001 09:45:54 AM
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    08 July 2009
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    None
//
{
# define TIME_SIZE 40

  static char time_buffer[TIME_SIZE];
  const struct std::tm *tm_ptr;
  std::time_t now;

  now = std::time ( NULL );
  tm_ptr = std::localtime ( &now );

  std::strftime ( time_buffer, TIME_SIZE, "%d %B %Y %I:%M:%S %p", tm_ptr );

  std::cout << time_buffer << "\n";

  return;
# undef TIME_SIZE
}