#------------------------------------------------------------------------------
#  matrix.py
#------------------------------------------------------------------------------
from random import uniform


class Matrix:
   """Class representing a rectangular matrix."""

   # built-in methods ---------------------------------------------------------

   def __init__(self, L=[]):
      """
      Initialize a Matrix object from a list of lists. If the list is empty,
      the resulting Matrix is empty (size 0x0).
      """

      # get number of rows and columns
      n = self.numRows = len(L)
      m = self.numCols = ( len(L[0]) if n>0 else 0 )
      self.elements = {}
      if n==0: 
         return
      # end if
      
      # build dictionary
      for i in range(n):
         if len(L[i])!=m:
            msg = f'could not create Matrix from ragged list:\n{L}'
            raise ValueError(msg)
         # end if
         for j in range(m):
            self.elements[(i+1,j+1)] = L[i][j]
         # end for
      # end for

   # end __init__()

   def __str__(self):

   def __eq__(self, other):


   # Matrix instance methods --------------------------------------------------

   def add(self, other):

   def sub(self, other):

   def scale(self, c):

   def trans(self):

   def mult(self, other):  


   # Matrix class methods -----------------------------------------------------

   def from_string(s=''):

   def identity(n):

   def randMatrix(n, m, a, b):


# end class Matrix ------------------------------------------------------------