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+#ifndef POLARDECOMPOSITION_H
+#define POLARDECOMPOSITION_H
+
+#include "btMatrix3x3.h"
+
+/**
+ * This class is used to compute the polar decomposition of a matrix. In
+ * general, the polar decomposition factorizes a matrix, A, into two parts: a
+ * unitary matrix (U) and a positive, semi-definite Hermitian matrix (H).
+ * However, in this particular implementation the original matrix, A, is
+ * required to be a square 3x3 matrix with real elements. This means that U will
+ * be an orthogonal matrix and H with be a positive-definite, symmetric matrix.
+ */
+class btPolarDecomposition
+{
+ public:
+
+
+ /**
+ * Creates an instance with optional parameters.
+ *
+ * @param tolerance - the tolerance used to determine convergence of the
+ * algorithm
+ * @param maxIterations - the maximum number of iterations used to achieve
+ * convergence
+ */
+ btPolarDecomposition(btScalar tolerance = btScalar(0.0001),
+ unsigned int maxIterations = 16);
+
+ /**
+ * Decomposes a matrix into orthogonal and symmetric, positive-definite
+ * parts. If the number of iterations returned by this function is equal to
+ * the maximum number of iterations, the algorithm has failed to converge.
+ *
+ * @param a - the original matrix
+ * @param u - the resulting orthogonal matrix
+ * @param h - the resulting symmetric matrix
+ *
+ * @return the number of iterations performed by the algorithm.
+ */
+ unsigned int decompose(const btMatrix3x3& a, btMatrix3x3& u, btMatrix3x3& h) const;
+
+ /**
+ * Returns the maximum number of iterations that this algorithm will perform
+ * to achieve convergence.
+ *
+ * @return maximum number of iterations
+ */
+ unsigned int maxIterations() const;
+
+ private:
+ btScalar m_tolerance;
+ unsigned int m_maxIterations;
+};
+
+/**
+ * This functions decomposes the matrix 'a' into two parts: an orthogonal matrix
+ * 'u' and a symmetric, positive-definite matrix 'h'. If the number of
+ * iterations returned by this function is equal to
+ * btPolarDecomposition::DEFAULT_MAX_ITERATIONS, the algorithm has failed to
+ * converge.
+ *
+ * @param a - the original matrix
+ * @param u - the resulting orthogonal matrix
+ * @param h - the resulting symmetric matrix
+ *
+ * @return the number of iterations performed by the algorithm.
+ */
+unsigned int polarDecompose(const btMatrix3x3& a, btMatrix3x3& u, btMatrix3x3& h);
+
+#endif // POLARDECOMPOSITION_H
+