# include <stdlib.h>
# include <stdio.h>
# include <math.h>

# include "fd1d_heat_explicit.h"

int main ( );
void fd1d_heat_explicit_test01 ( );
void bc_test01 ( int x_num, double x[], double t, double h[] );
double *ic_test01 ( int x_num, double x[], double t );
double *rhs_test01 ( int x_num, double x[], double t );

/******************************************************************************/

int main ( )

/******************************************************************************/
/*
  Purpose:

    MAIN is the main program for FD1D_HEAT_EXPLICIT_TEST.

  Discussion:

    FD1D_HEAT_EXPLICIT_TEST tests FD1D_HEAT_EXPLICIT.

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    26 January 2012

  Author:

    John Burkardt
*/
{
  timestamp ( );
  printf ( "\n" );
  printf ( "FD1D_HEAT_EXPLICIT_TEST:\n" );
  printf ( "  C version.\n" );
  printf ( "  Test the FD1D_HEAT_EXPLICIT library.\n" );

  fd1d_heat_explicit_test01 ( );
/*
  Terminate.
*/
  printf ( "\n" );
  printf ( "FD1D_HEAT_EXPLICIT_TEST:\n" );
  printf ( "  Normal end of execution.\n" );
  printf ( "\n" );
  timestamp ( );

  return 0;
}
/******************************************************************************/

void fd1d_heat_explicit_test01 ( )

/******************************************************************************/
/*
  Purpose:

    FD1D_HEAT_EXPLICIT_TEST01 does a simple test problem

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    26 January 2012

  Author:

    John Burkardt
*/
{
  double cfl;
  double dt;
  double *h;
  double *h_new;
  double *hmat;
  int i;
  int j;
  double k;
  double *t;
  double t_max;
  double t_min;
  int t_num;
  double *x;
  double x_max;
  double x_min;
  int x_num;

  printf ( "\n" );
  printf ( "FD1D_HEAT_EXPLICIT_TEST01:\n" );
  printf ( "  Compute an approximate solution to the time-dependent\n" );
  printf ( "  one dimensional heat equation:\n" );
  printf ( "\n" );
  printf ( "    dH/dt - K * d2H/dx2 = f(x,t)\n" );
  printf ( "\n" );
  printf ( "  Run a simple test case.\n" );
/*
  Heat coefficient.
*/
  k = 0.002;
/*
  X_NUM is the number of equally spaced nodes to use between 0 and 1.
*/
  x_num = 21;
  x_min = 0.0;
  x_max = 1.0;
  x = r8vec_linspace_new ( x_num, x_min, x_max );
/*
  T_NUM is the number of equally spaced time points between 0 and 10.0.
*/
  t_num = 201;
  t_min = 0.0;
  t_max = 80.0;
  dt = ( t_max - t_min ) / ( double ) ( t_num - 1 );
  t = r8vec_linspace_new ( t_num, t_min, t_max );
/*
  Get the CFL coefficient.
*/
  cfl = fd1d_heat_explicit_cfl ( k, t_num, t_min, t_max, x_num, x_min, x_max );
/*
  Running the code produces an array H of temperatures H(t,x),
  and vectors x and t.
*/
  h = ic_test01 ( x_num, x, t[0] );
  bc_test01 ( x_num, x, t[0], h );

  hmat = ( double * ) malloc ( x_num * t_num * sizeof ( double ) );

  j = 0;
  for ( i = 0; i < x_num; i++ )
  {
    hmat[i+j*x_num] = h[i];
  }

  for ( j = 1; j < t_num; j++ )
  {
    h_new = fd1d_heat_explicit ( x_num, x, t[j-1], dt, cfl, rhs_test01, bc_test01, h );

    for ( i = 0; i < x_num; i++ )
    {
      hmat[i+j*x_num] = h_new[i];
      h[i] = h_new[i];
    }
    free ( h_new );
  }
/*
  Write the data to files.
*/
  r8mat_write ( "h_test01.txt", x_num, t_num, hmat );
  r8vec_write ( "t_test01.txt", t_num, t );
  r8vec_write ( "x_test01.txt", x_num, x );

  free ( h );
  free ( hmat );
  free ( t );
  free ( x );

  return;
}
/******************************************************************************/

void bc_test01 ( int x_num, double x[], double t, double h[] )

/******************************************************************************/
/*
  Purpose:

    BC_TEST01 evaluates the boundary conditions for problem 1.

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    26 January 2012

  Author:

    John Burkardt

  Parameters:

    Input, int X_NUM, the number of nodes.

    Input, double X[X_NUM], the node coordinates.

    Input, double T, the current time.

    Input, double H[X_NUM], the current heat values.

    Output, double H[X_NUM], the current heat values, after boundary
    conditions have been imposed.
*/
{
  h[0]  = 90.0;
  h[x_num-1] = 70.0;

  return;
}
/******************************************************************************/

double *ic_test01 ( int x_num, double x[], double t )

/******************************************************************************/
/*
  Purpose:

    IC_TEST01 evaluates the initial condition for problem 1.

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    26 January 2012

  Author:

    John Burkardt

  Parameters:

    Input, int X_NUM, the number of nodes.

    Input, double X[X_NUM], the node coordinates.

    Input, double T, the initial time.

    Output, double H[X_NUM], the heat values at the initial time.
*/
{
  int j;
  double *h;

  h = ( double * ) malloc ( x_num * sizeof ( double ) );

  for ( j = 0; j < x_num; j++ )
  {
    h[j] = 50.0;
  }
  return h;
}
/******************************************************************************/

double *rhs_test01 ( int x_num, double x[], double t )

/******************************************************************************/
/*
  Purpose:

    RHS_TEST01 evaluates the right hand side for problem 1.

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    26 January 2012

  Author:

    John Burkardt

  Parameters:

    Input, int X_NUM, the number of nodes.

    Input, double X[X_NUM], the node coordinates.

    Input, double T, the current time.

    Output, double RHS_TEST01[X_NUM], the source term.
*/
{
  int i;
  double *value;

  value = ( double * ) malloc ( x_num * sizeof ( double ) );

  for ( i = 0; i < x_num; i++ )
  {
    value[i] = 0.0;
  }
  return value;
}