A general question about its capabilities. The library is excellent for getting updated statistics as one adds values to an accumulator. I have one wrinkle. I have long running time series, and wish to evaluate statistics on a window of the data, say the last 100 values. Can the Accumulator framework be used in a 'windowed' situation? For example, for a similar smaller scale project, I used a queue ( to represent a specific time frame) to to keep track of a series of values. As values are added to the queue, they are added into a statistic. As the values are dropped from the qeue, the values are removed from a statistic. I understand that rounding errors may accumulate over time, but current experiments indicate that the error magnitude by the end of the series is not noticable. If code helps to make sense, here is what I did on a smaller scale with simple statistics (some may comment on the lack of getters and setters, but at least the concept is there): class CRunningStats { public: CRunningStats(void); CRunningStats(double BBMultiplier); virtual ~CRunningStats(void); void SetBBMultiplier( double dbl ) { m_BBMultiplier = dbl; }; double GetBBMultiplier( void ) { return m_BBMultiplier; }; double b2; // acceleration double b1; // slope double b0; // offset double meanY; double RR; double R; double SD; double BBUpper, BBLower; void Add( double, double ); void Remove( double, double ); virtual void CalcStats( void ); protected: unsigned int nX, nY; double SumXX, SumX, SumXY, SumY, SumYY; double Sxx, Sxy, Syy; double SST, SSR, SSE; double m_BBMultiplier; private: }; CRunningStats::CRunningStats(void) : b2( 0 ), b1( 0 ), b0( 0 ), SumXX( 0 ), SumX( 0 ), SumXY( 0 ), SumY( 0 ), SumYY( 0 ), nX( 0 ), m_BBMultiplier( 2.0 ) { } CRunningStats::CRunningStats( double BBMultiplier ) : b2( 0 ), b1( 0 ), b0( 0 ), SumXX( 0 ), SumX( 0 ), SumXY( 0 ), SumY( 0 ), SumYY( 0 ), nX( 0 ), m_BBMultiplier( BBMultiplier ) { } CRunningStats::~CRunningStats(void) { } void CRunningStats::Add(double x, double y) { SumXX += x * x; SumX += x; SumXY += x * y; SumY += y; SumYY += y * y; nX++; } void CRunningStats::Remove(double x, double y) { SumXX -= x * x; SumX -= x; SumXY -= x * y; SumY -= y; SumYY -= y * y; nX--; } void CRunningStats::CalcStats() { if ( nX > 1 ) { double oldb1 = b1; Sxx = SumXX - ( SumX * SumX ) / nX; Sxy = SumXY - ( SumX * SumY ) / nX; Syy = SumYY - ( SumY * SumY ) / nX; SST = Syy; SSR = ( Sxy * Sxy ) / Sxx; SSE = SST - SSR; RR = SSR / SST; R = Sxy / sqrt(Sxx * Syy); //SD = Math.Sqrt(Syy / (Xcnt - 1)); SD = sqrt(Syy / nX); meanY = SumY / nX; double BBOffset = m_BBMultiplier * SD; BBUpper = meanY + BBOffset; BBLower = meanY - BBOffset; b1 = ( nX > 1 ) ? Sxy / Sxx : 0; b0 = (1 / nX) * ( SumY - b1 * SumX ); b2 = b1 - oldb1; // *** do this differently } } -- Scanned for viruses and dangerous content at http://www.oneunified.net and is believed to be clean.