tempest/examples/pgcl/lotkavolterra.pgcl

function lotkavolterra() {

	int goats     := 100;
	int tigers    := 4;
	int dwellTime := 0;
	int curTime   := 0;
	int b         := 0;

	while(tigers > 0 & goats > 0) {

		dwellTime := 0;
		b := 1;

		if(goats > 0 & tigers > 0) {

			// geometric distribution with p = 0.5
			while (b >= 1) {
				{b := 1;} [0.5] {b := 0;}
				dwellTime := dwellTime + 1;
			}
			curTime := curTime + dwellTime;
			{tigers := tigers + 1;} [0.2] {{goats := goats - 1;} [0.1] {tigers := tigers - 1;}}

		} else { if(goats > 0) {

			// geometric distribution with p = 0.5
			while (b >= 1) {
				{b := 1;} [0.5] {b := 0;}
				dwellTime := dwellTime + 1;
			}
			curTime := curTime + dwellTime;
			goats   := goats + 1;

		} else { if(tigers > 0) {

			// geometric distribution with p = 0.5
			while (b >= 1) {
				{b := 1;} [0.5] {b := 0;}
				dwellTime := dwellTime + 1;
			}
			curTime := curTime + dwellTime;
			tigers  := tigers - 1;

		} } }

	}

}