class_docstr: A matrix group of linear (not affine) transformations with matrices having a specific dtype.
code: def _getcoords(self):
      return self.function_domain
  
imports: import numpy
  from nipy.core.api import AffineTransform, CoordinateSystem
  from nipy.core.reference.coordinate_map import compose
  from nipy.core.reference.coordinate_map import product
label_desc: Use image node_id 3 for calling the MatrixGroup obj's underlying member method code with example usage: obj._getcoords() and returns: self