New Matrix3F class added in gfx.

ui/gfx/matrix3_f.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_MATRIX3_F_H_
+#define UI_GFX_MATRIX3_F_H_
+
+#include "ui/gfx/vector3d_f.h"
+
+namespace gfx {
+
+class UI_EXPORT Matrix3F {
+ public:
+  typedef float ScalarType;
+  typedef Vector3dF VectorType;
+
+  Matrix3F(const Matrix3F& rhs);
+  ~Matrix3F();
+
+  bool IsEqual(const Matrix3F& rhs) const;
+
+  // Element-wise comparison with given precision. A convenience method
+  // primairly intended for unit tests.
+  bool IsNear(const Matrix3F& rhs, ScalarType precision) const;

[danakj, 2013/01/31 22:38:30]

nit: primarily

If this is just for tests, can you move it to the unittest file please?

[motek., 2013/01/31 23:29:56]

On the second thought: I may actually need it in practice soon enough (will not
want to call eigensolver on covariance matrix if it is close to 0).

+
+  ScalarType get(int i, int j) const;
+  void set(int i, int j, ScalarType v);
+  void set(ScalarType v);
+  void set(ScalarType m00, ScalarType m01, ScalarType m02,
+           ScalarType m10, ScalarType m11, ScalarType m12,
+           ScalarType m20, ScalarType m21, ScalarType m22);
+
+  VectorType GetColumn(int i) const;
+  void SetColumn(int i, const VectorType& c);
+
+  // Returns an inverse of this if the matrix is non-singular, zero (== Zero())
+  // otherwise.
+  Matrix3F Inverse() const;
+
+  // Value of the determinant of the matrix.
+  ScalarType Determinant() const;
+
+  // Trace (sum of diagonal elements) of the matrix.
+  ScalarType Trace() const;
+
+  // Compute eigenvalues and (optionally) normalized eigenvectors of
+  // a positive defnite matrix *this. Eigenvectors are computed only if
+  // non-null |eigenvectors| matrix is passed. If it is NULL, the routine
+  // will not attempt to compute eigenvectors but will still return eigenvalues
+  // if they can be computed.
+  // If eigenvalues cannot be computed (the matrix does not meet constraints)
+  // the 0-vector is returned. Note that to retrieve eigenvalues, the matrix
+  // only needs to be symmetric while eigenvectors require it to be
+  // positive-definite. Passing a non-positive definite matrix will result in
+  // NaNs in vectors which cannot be computed.
+  // Eigenvectors are placed as column in |eigenvectors| in order corresponding
+  // to eigenvalues.
+  VectorType SolveEigenproblem(Matrix3F* eigenvectors) const;
+
+  static Matrix3F Zeros();
+  static Matrix3F Ones();
+  static Matrix3F Identity();
+  static Matrix3F FromOuterProduct(const VectorType& a, const VectorType& bt);
+
+ private:
+  ScalarType data_[9];
+
+  Matrix3F();  // Uninitialized default.
+};
+
+inline bool operator==(const Matrix3F& lhs, const Matrix3F& rhs) {
+  return lhs.IsEqual(rhs);
+}
+
+}  // namespace gfx
+
+#endif  // UI_GFX_MATRIX3_F_H_