Eigen defines several typedef shortcuts for most common 1D and 2D array types.

The general patterns are the following:

ArrayRowsColsType where Rows and Cols can be 2,3,4 for fixed size square matrices or X for dynamic size, and where Type can be i for integer, f for float, d for double, cf for complex float, cd for complex double.

For example, Array33d is a fixed-size 3x3 array type of doubles, and ArrayXXf is a dynamic-size matrix of floats.

There are also ArraySizeType which are self-explanatory. For example, Array4cf is a fixed-size 1D array of 4 complex floats.

With [c++11], template alias are also defined for common sizes. They follow the same pattern as above except that the scalar type suffix is replaced by a template parameter, i.e.:

• ArrayRowsCols<Type> where Rows and Cols can be 2,3,4, or X for fixed or dynamic size.
• ArraySize<Type> where Size can be 2,3,4 or X for fixed or dynamic size 1D arrays.

See also

class Array

template<typename Type >
using	Eigen::Array2 = Array< Type, 2, 1 >
	[c++11]
template<typename Type >
using	Eigen::Array22 = Array< Type, 2, 2 >
	[c++11]
template<typename Type >
using	Eigen::Array2X = Array< Type, 2, Dynamic >
	[c++11]
template<typename Type >
using	Eigen::Array3 = Array< Type, 3, 1 >
	[c++11]
template<typename Type >
using	Eigen::Array33 = Array< Type, 3, 3 >
	[c++11]
template<typename Type >
using	Eigen::Array3X = Array< Type, 3, Dynamic >
	[c++11]
template<typename Type >
using	Eigen::Array4 = Array< Type, 4, 1 >
	[c++11]
template<typename Type >
using	Eigen::Array44 = Array< Type, 4, 4 >
	[c++11]
template<typename Type >
using	Eigen::Array4X = Array< Type, 4, Dynamic >
	[c++11]
template<typename Type >
using	Eigen::ArrayX = Array< Type, Dynamic, 1 >
	[c++11]
template<typename Type >
using	Eigen::ArrayX2 = Array< Type, Dynamic, 2 >
	[c++11]
template<typename Type >
using	Eigen::ArrayX3 = Array< Type, Dynamic, 3 >
	[c++11]
template<typename Type >
using	Eigen::ArrayX4 = Array< Type, Dynamic, 4 >
	[c++11]
template<typename Type >
using	Eigen::ArrayXX = Array< Type, Dynamic, Dynamic >
	[c++11]