/*
************************************************************************ 
* EqHeat_M.java: Solve heat equation using with finite differences
* 
* copyright RH Landau, Oregon State Univ, 8/99 *  
*  
* 
* modified 8/01 DH McIntyre to create output file for Maple surfdata plot.
* File contains (x,y,z) data points where x=time, y=position, z=temperature
* 
************************************************************************ 
*/ 
 
import java.io.*;                      /* Import input-output Library */ 
 
public class EqHeat_xyz 
{ 
// Class constants  
public static final int NX = 51; 			/* grid size */ 
public static final int NT = 101;			/* Number time points to save */ 
public static final int DT = 200;			/* Number of time iterations/save*/
public static final double THC = 0.12;		/* thermal conductivity*/ 
public static final double SPH = 0.113;		/* specific heat */ 
public static final double RHO = 15.;		/* density */ 
 
// method must throw exceptions if does not handle them. 
public static void main(String[] argv) throws IOException, 
FileNotFoundException  
{  
int ix, t; 
double[] [] u = new double[NX][2]; /* 2-D array declared, allocated */ 
double cons;  
 
// Open file EqHeat.dat for output data, use JDK 1.1 methods  
 
PrintWriter q = new PrintWriter( 
new FileOutputStream("EqHeat_xyz.dat"), true); 



/*Print data to file for input to Maple
* Maple data files want numbers separated by spaces
* We only ouput z here, so x and y values are assumed to go from 
* 0 to (N-1) where N is the number of values (per line for x, # lines for y)
*/
 
for(ix=1; ix < NX-1; ix++) u[ix][0]=100.; /* t=0 all points at 100 C */ 
for(t=0; t < 2; t++) /* except the endpoints */ 
{ 
u[0][t] = 0.; 
u[NX-1][t] = 0.; 
}  
 
cons=THC/(SPH*RHO); /* material constants */ 
 
for(t=1; t < NT*DT; t++) /* loop over max timesteps */ 
	{ 
	for(ix=1; ix < NX-1; ix++) /* loop over space */ 
		{ 
		u[ix][1] = u[ix][0]+cons*(u[ix+1][0]+u[ix-1][0]-2.0*u[ix][0]); 
		} 
		if((t%DT==0) || (t==1)) /* save every DT time steps */ 
			{ 
			for(ix=0 ; ix < NX; ix++) 
				{
				q.println(t+" "+ix+" "+u[ix][1]); //output data with spaces
				}
			} 
	for(ix=1; ix < NX-1; ix++) u[ix][0]=u[ix][1]; /*shift new values
	to old */ 
	}  //end time loop
System.out.println("data stored in EqHeat_xyz.dat");  
}  //end main 
}//end class