class_docstr: Subclass of AffineTransform that is Linear as opposed to AffineTransform, i.e. the translation is 0.
  
  It is instantiated with an matrix of shape (ndim,ndim) instead of (ndim+1,ndim+1)
code: def _getmatrix(self):
      return self.affine[:-1, :-1]
  
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 1 for calling the Linear obj's underlying member method code with example usage: obj._getmatrix() and returns: self