#!/usr/local/bin/tcc -run
#include <stdio.h>
#include <math.h>

void out(float dt, int n, int JJ, float u[]){
	int j;
	printf("%6.2f |", dt*n);
	for(j=0; j<=JJ; j++){
		printf("%6.3f ", u[j]);
	}
	printf("\n");
}

int main(void){
	int NM=31;
	int JJ=30;
	float dx=3.0/JJ;
	float dt=0.01;
	int NN=30;
	float c=0.5;
	float r=c*dt/dx;
	int j,n;
	float x[NM],f[NM],u[NM],uu[NM];
	
	for(j=0; j<=JJ; j++){
		f[j]=sin(6.0*x[j]);
		if(x[j]>4.0*atan(1.0)/3.0) f[j]=0.0;
	}
	
	for(j=0; j<=JJ; j++){
		u[j]=f[j];
		uu[j]=f[j];
	}
	out(dt,0,JJ,u);
	
	for(n=1; n<=NN; n++){
		for(j=1; j<=JJ; j++){
			uu[j]=(1-r)*u[j]+r*u[j-1];
		}
		out(dt,n,JJ,uu);
		for(j=0; j<=JJ; j++){
			u[j]=uu[j];
		}
	}
	return 0;
}