Mat3 class

  This class represents a 3x3 matrix

Constructor:
  Mat3(m11,m12,m13,
       m21,m22,m23,
       m31,m32,m33) 

Methods:
  elements can be accessed by matrix indexing:
    m[0,0] = 42
    print m[0,0]
  
  fromList( list ) - assign members from a list of lists

  transpose(mat) - returns transpose of matrix

SymMat3 class

  A 3x3 symmetric matrix class.

Constructor:
  SymMat3(m11,
          m12,m22,
          m13,m23,m33) specification of lower triangular elements is optional

Methods:
  elements can be accessed by matrix indexing, as described for the Mat3 class.


The following functions are defined:

  eigen(mat) - returns a list of eigen value/vector pairs in an EigenPair 
              structure with accessors:
                            value(), vector()

  transpose(mat) - returns transpose of matrix

  rotVector(vec, angle) - return matrix corresponding to rotation about 
                          3-vector vec by angle (in radians)