private void ComputeRelativePerf(int i)
{
KeyValuePair <DateTime, double> p = datesAndValuation.ElementAt(i);
DateTime currentDate = p.Key;
int benchIdx = index.findDateIndex(currentDate);
double perfC = perf.ElementAt(i), perfB = index.GetPerformanceAt(benchIdx);
relativePerf.Add((double)(perfC - perfB));
}