Eigen
3.3.9

Eigen defines several typedef shortcuts for most common matrix and vector types.
The general patterns are the following:
MatrixSizeType
where Size
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, Matrix3d
is a fixedsize 3x3 matrix type of doubles, and MatrixXf
is a dynamicsize matrix of floats.
There are also VectorSizeType
and RowVectorSizeType
which are selfexplanatory. For example, Vector4cf
is a fixedsize vector of 4 complex floats.