/// <summary> /// Construct packed versions of input matrices, and then use sparse row/column dot /// to compute elements of output matrix. This is faster. But still relatively expensive. /// </summary> void multiply_fast(SymmetricSparseMatrix M2in, ref SymmetricSparseMatrix Rin, bool bParallel) { int N = Rows; if (M2in.Rows != N) { throw new Exception("SymmetricSparseMatrix.Multiply: matrices have incompatible dimensions"); } if (Rin == null) { Rin = new SymmetricSparseMatrix(); } SymmetricSparseMatrix R = Rin; // require alias for use in lambda below PackedSparseMatrix M = new PackedSparseMatrix(this); M.Sort(); PackedSparseMatrix M2 = new PackedSparseMatrix(M2in, true); M2.Sort(); // Parallel variant is vastly faster, uses spinlock to control access to R if (bParallel) { // goddamn SpinLock is in .Net 4 //SpinLock spin = new SpinLock(); gParallel.ForEach(Interval1i.Range(N), (r1i) => { for (int c2i = r1i; c2i < N; c2i++) { double v = M.DotRowColumn(r1i, c2i, M2); if (Math.Abs(v) > math.MathUtil.ZeroTolerance) { //bool taken = false; //spin.Enter(ref taken); //Debug.Assert(taken); //R[r1i, c2i] = v; //spin.Exit(); lock (R) { R[r1i, c2i] = v; } } } }); } else { for (int r1i = 0; r1i < N; r1i++) { for (int c2i = r1i; c2i < N; c2i++) { double v = M.DotRowColumn(r1i, c2i, M2); if (Math.Abs(v) > math.MathUtil.ZeroTolerance) { R[r1i, c2i] = v; } } } } }
// returns this*this (requires less memory) public SymmetricSparseMatrix Square(bool bParallel = true) { SymmetricSparseMatrix R = new SymmetricSparseMatrix(); PackedSparseMatrix M = new PackedSparseMatrix(this); M.Sort(); // Parallel variant is vastly faster, uses spinlock to control access to R if (bParallel) { // goddamn SpinLock is in .Net 4 //SpinLock spin = new SpinLock(); gParallel.ForEach(Interval1i.Range(N), (r1i) => { for (int c2i = r1i; c2i < N; c2i++) { double v = M.DotRowColumn(r1i, c2i, M); if (Math.Abs(v) > math.MathUtil.ZeroTolerance) { //bool taken = false; //spin.Enter(ref taken); //Debug.Assert(taken); //R[r1i, c2i] = v; //spin.Exit(); lock (R) { R[r1i, c2i] = v; } } } }); } else { for (int r1i = 0; r1i < N; r1i++) { for (int c2i = r1i; c2i < N; c2i++) { double v = M.DotRowColumn(r1i, c2i, M); if (Math.Abs(v) > math.MathUtil.ZeroTolerance) { R[r1i, c2i] = v; } } } } return(R); }