diff options
| -rw-r--r-- | Eigen/src/Core/Matrix.h | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/Eigen/src/Core/Matrix.h b/Eigen/src/Core/Matrix.h index d6b54c86f..335150318 100644 --- a/Eigen/src/Core/Matrix.h +++ b/Eigen/src/Core/Matrix.h @@ -33,7 +33,7 @@ * The Matrix class is the work-horse for all \em dense matrices and vectors within Eigen. Vectors are matrices with one column, * and row-vectors are matrices with one row. * - * The Matrix class encompasses \em both fixed-size and dynamic-size objects. + * The Matrix class encompasses \em both fixed-size and dynamic-size objects (see note below). * * \param _Scalar Numeric type, i.e. float, double, int * \param _Rows Number of rows, or \b Dynamic @@ -42,13 +42,13 @@ * \param _MaxRows Maximum number of rows. Defaults to \a _Rows. See note below. * \param _MaxCols Maximum number of columns. Defaults to \a _Cols. See note below. * - * \note <b>Fixed-size versus dynamic-size</b> + * \note <b>Fixed-size versus dynamic-size:</b> * Fixed-size means that the numbers of rows and columns are known are compile-time. In this case, Eigen allocates the array * of coefficients as a fixed-size array on the stack. This makes sense for very small matrices, typically up to 4x4, sometimes up * to 16x16. Larger matrices should be declared as dynamic-size even if one happens to know their size at compile-time. * * Dynamic-size means that the numbers of rows or columns are not necessarily known at compile-time. In this case they are runtime variables, - * and the array of coefficients is allocated dynamically, typically on the heap (See Note [*] below). + * and the array of coefficients is allocated dynamically, typically on the heap (See note on heap allocation below). * * Note that dense matrices, be they Fixed-size or Dynamic-size, <em>do not</em> expand dynamically in the sense of a std::map. * If you want this behavior, see the Sparse module. @@ -60,6 +60,10 @@ * exceed a certain value. This happens when taking dynamic-size blocks inside fixed-size matrices: in this case _MaxRows and _MaxCols * are the dimensions of the original matrix, while _Rows and _Cols are Dynamic. * + * \note <b> Heap allocation:</b> + * On the Linux platform, for small enough arrays, Eigen will avoid heap allocation and instead will use alloca() to perform a dynamic + * allocation on the stack. + * * Eigen provides a number of typedefs to make working with matrices and vector simpler: * * For example: |