def CreateEncoderMatrix(self):
self.encoderMatrix = genericmatrix.GenericMatrix(
(self.n, self.k), 0, 1, self.field.Add, self.field.Subtract,
self.field.Multiply, self.field.Divide)
self.encoderMatrix[0, 0] = 1
for i in range(0, self.n):
term = 1
for j in range(0, self.k):
self.encoderMatrix[i, j] = term
term = self.field.Multiply(term, i)
def PrepareDecoder(self, unErasedLocations):
"""
Function: PrepareDecoder(erasedTerms)
Description: The input unErasedLocations is a list of the first
self.k elements of the codeword which were
NOT erased. For example, if the 0th, 5th,
and 7th symbols of a (16,5) code were erased,
then PrepareDecoder([1,2,3,4,6]) would
properly prepare for decoding.
"""
if (len(unErasedLocations) != self.k):
raise ValueError('input must be exactly length k')
limitedEncoder = genericmatrix.GenericMatrix(
(self.k, self.k), 0, 1, self.field.Add, self.field.Subtract,
self.field.Multiply, self.field.Divide)
for i in range(0, self.k):
limitedEncoder.SetRow(
i, self.encoderMatrix.GetRow(unErasedLocations[i]))
self.decoderMatrix = limitedEncoder.Inverse()