Exemple #1
0
        public static void ComputeMeanCovariance(IList<Vector2> pts, out Vector2 mean, out Matrix2 cov)
        {
            // for better numerical stability, use a two-pass method where we first compute the mean
            double sum_x = 0, sum_y = 0;
            for (int i = 0; i < pts.Count; i++) {
                sum_x += pts[i].X;
                sum_y += pts[i].Y;
            }

            double avg_x = sum_x/(double)pts.Count;
            double avg_y = sum_y/(double)pts.Count;

            // now compute variances and covariances
            double sum_x2 = 0, sum_y2 = 0, sum_xy = 0;
            for (int i = 0; i < pts.Count; i++) {
                double dx = pts[i].X - avg_x;
                double dy = pts[i].Y - avg_y;

                sum_x2 += dx*dx;
                sum_y2 += dy*dy;
                sum_xy += dx*dy;
            }

            double var_x = sum_x2/(double)pts.Count;
            double var_y = sum_y2/(double)pts.Count;
            double cov_xy = sum_xy/(double)pts.Count;

            mean = new Vector2(avg_x, avg_y);
            cov = new Matrix2(var_x, cov_xy, cov_xy, var_y);
        }
Exemple #2
0
        public Matrix4 Inverse()
        {
            Matrix2 invA = SubmatrixA().Inverse();
            Matrix2 B    = SubmatrixB();
            Matrix2 C    = SubmatrixC();

            Matrix2 invSchurComp = (SubmatrixD() - C * invA * B).Inverse();

            return(Matrix4.FromSubmatrix(
                       invA + invA * B * invSchurComp * C * invA, -invA * B * invSchurComp,
                       -invSchurComp * C * invA, invSchurComp));
        }
Exemple #3
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        public static Matrix4 FromSubmatrix(
            Matrix2 A, Matrix2 B,
            Matrix2 C, Matrix2 D)
        {
            Matrix4 ret = new Matrix4();

            for (int i = 0; i < 2; i++)
            {
                for (int j = 0; j < 2; j++)
                {
                    ret[i, j]         = A[i, j];
                    ret[i + 2, j]     = C[i, j];
                    ret[i, j + 2]     = B[i, j];
                    ret[i + 2, j + 2] = D[i, j];
                }
            }

            return(ret);
        }
        public bool Intersect(Line l, out Vector2 pt, out Vector2 K)
        {
            Vector2 P = P1 - P0;
            Vector2 S = l.P1 - l.P0;

            double cross = S.Cross(P);
            if (Math.Abs(cross) < 1e-10) {
                pt = default(Vector2);
                K = default(Vector2);
                return false;
            }

            Matrix2 A = new Matrix2(-S.Y, S.X, -P.Y, P.X);
            K = A*(l.P0 - P0)/cross;

            if (K.X >= 0 && K.X <= 1) {
                pt = P0 + P*K.X;
                return true;
            }
            else {
                pt = default(Vector2);
                return false;
            }
        }
        public bool Intersect(LineSegment l, out Vector2 pt, out Vector2 K)
        {
            Vector2 P = P1 - P0;
            Vector2 S = l.P1 - l.P0;

            Matrix2 A = new Matrix2(P.X, -S.X, P.Y, -S.Y);

            if (Math.Abs(A.Determinant()) < 1e-10) {
                pt = default(Vector2);
                K = default(Vector2);
                return false;
            }

            K = A.Inverse()*(l.P0 - P0);

            if (K.X >= 0 && K.X <= 1 && K.Y >= 0 && K.Y <= 1) {
                pt = P0 + P*K.X;
                return true;
            }
            else {
                pt = default(Vector2);
                return false;
            }
        }
Exemple #6
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 public HRIPDF(Vector2 mean, Matrix2 sigma)
 {
     this.mean = mean;
     this.sigma = sigma;
 }
Exemple #7
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        public static Matrix4 FromSubmatrix(
			Matrix2 A, Matrix2 B,
			Matrix2 C, Matrix2 D)
        {
            Matrix4 ret = new Matrix4();

            for (int i = 0; i < 2; i++)
            {
                for (int j = 0; j < 2; j++)
                {
                    ret[i, j] = A[i, j];
                    ret[i + 2, j] = C[i, j];
                    ret[i, j + 2] = B[i, j];
                    ret[i + 2, j + 2] = D[i, j];
                }
            }

            return ret;
        }