//Linda Mac Phee
//Feb 96



//This program calculates the time it take s molecules
//of ammonia to leave the bottle and arrive a meter away
//in a density strong enough to smell





//volume of sphere	4/3II(01)^3 == 4/3II(dr)^3
//area of ammonia surface	II(dr)^2
//volume of all other shells 4IIR^2dr





//function librarys
#include	<stdio.h>


//globals
#define 		PI 	3.1415
#define 		TM 	2		//past and current time
#define 		SHELL 100  //.5 cm distances from origin







int main( void )
{

	//declare variables
	int		i, j;		//loop control
	int		p, m;		//loop control
	double		in, out;	//temp holding for calculations
	double		n0;		//number molecules coming off surface
	double		r0;		//inner sphere
	double		r1;		//1st shell
	double		dr;		//change in shell size
	double		data_array[TM][SHELL];	    //1st row temp holding
						    //2nd row  current
						    //columns are shells (distance from origin)



	//initalize variables
	r0 = .5;		//cm
	r1 = 1.5;		//cm
	dr = 0.5;		//cm
	n0 = 100000;		//# molecules

	for(i=0; i<2; i++){

		for(j=0; j<100; j++){

			data_array[i][j] = 0;

		}//end j loop

	}//end i loop





//*****watch don't go off ends of array



	//time step loop

	//want 100,000 iterations

	for(m=0; m < 10; m++){

		//copy data for next step and dump

		//copy from 1st row to oth row

		for(p = 0; p < SHELL; p++){

			data_array[0][p] = data_array[1][p];

		}//end for loop transfering data



		//step through shells loop

		//100 iterations through all shells to 1 meter

		//or until 0 which ever is first

		for(p=0; (p < 10); p++){



			//if shell is innermost

			if(p == 0){

				printf("\n iteration # %d  ",m);

				in = ((.375)*(n0) + (1/9)*(data_array[0][1]));

				out = ((.375)*(data_array[0][0]) +  (.75)*(data_array[0][0]));

				data_array[1][p] = in - out;

			}//end if inner most shell



			//if 1st shell

			if(p == 1){

				in = ((.75)*(data_array[0][0]) + (.16)*(data_array[0][2]));

				out = ((1/9)*(data_array[0][1]) + (4/9)*(data_array[0][1]));

				data_array[1][1] = in - out;

			}//end if 1st shell



			//all other shells

			if(p > 1){

				in = (p*p)/((p-.5)*(p-.5))*(data_array[0][p-1]) +

						((p+1)*(p+1))/((p + 1.5)*(p + 1.5))*(data_array[0][p+1]);

				out = (p*p)/((p+.5)*(p*.5))*(data_array[0][p])

						+ ((p+1)*(p+1))/((p+.5)*(p+.5))*(data_array[0][p]);

				data_array[1][p] = (.25 * in) - (.25 * out);

			}//end if all other shells

		printf (  "  %ld", (long)data_array[1][p]);



		}//end inside loop

	}//end outer for loop

}  //end function