public Grid computeNextGeneration(Grid currentGeneration) {
logGridDetails(currentGeneration);
Grid nextGeneration = new Grid(currentGeneration.size());
for (int x = 0; x < currentGeneration.size(); x++) {
for (int y = 0; y < currentGeneration.size(); y++) {
Grid.Cell presentCell = currentGeneration.cellAt(x, y);
Grid.Cell futureCell = nextGeneration.cellAt(x, y);
int livingNeighborsCount = currentGeneration.countLivingNeighbors(x, y);
logCellDetails(x, y, presentCell, livingNeighborsCount);
applyRules(presentCell, futureCell, livingNeighborsCount);
}
}
generation++;
return nextGeneration;
}
/**
* @param args Command arguments.
* @throws GridException If failed.
*/
public static void main(String[] args) throws GridException {
// Starts grid.
Grid grid = args.length == 0 ? G.start() : G.start(args[0]);
try {
// Create portfolio.
GridCredit[] portfolio = new GridCredit[5000];
Random rnd = new Random();
// Generate some test portfolio items.
for (int i = 0; i < portfolio.length; i++) {
portfolio[i] =
new GridCredit(
50000 * rnd.nextDouble(), // Credit amount.
rnd.nextInt(1000), // Credit term in days.
rnd.nextDouble() / 10, // APR.
rnd.nextDouble() / 20 + 0.02 // EDF.
);
}
// Forecast horizon in days.
int horizon = 365;
// Number of Monte-Carlo iterations.
int iter = 10000;
// Percentile.
double percentile = 0.95;
// Mark the stopwatch.
long start = System.currentTimeMillis();
// Calculate credit risk and print it out.
// As you can see the grid enabling is completely hidden from the caller
// and it is fully transparent to him. In fact, the caller is never directly
// aware if method was executed just locally or on the 100s of grid nodes.
// Credit risk crdRisk is the minimal amount that creditor has to have
// available to cover possible defaults.
double crdRisk =
grid.reduce(
SPREAD,
closures(grid.size(), portfolio, horizon, iter, percentile),
new R1<Double, Double>() {
/** Collected values sum. */
private double sum;
/** Collected values count. */
private int count;
/** {@inheritDoc} */
@Override
public boolean collect(Double e) {
sum += e;
count++;
return true;
}
/** {@inheritDoc} */
@Override
public Double apply() {
return sum / count;
}
});
X.println(
"Credit risk [crdRisk="
+ crdRisk
+ ", duration="
+ (System.currentTimeMillis() - start)
+ "ms]");
}
// We specifically don't do any error handling here to
// simplify the example. Real application may want to
// add error handling and application specific recovery.
finally {
// Stops grid.
G.stop(true);
}
}
