def sumOfSubmodules(self, other):
"""
Return module which is sum of self and other.
"""
if self.row != other.row:
raise matrix.MatrixSizeError()
N = self.copy()
N.extendColumn(other)
module = Submodule.fromMatrix(N)
module.toHNF()
return module
def intersectionOfSubmodules(self, other):
"""
Return module which is intersection of self and other.
"""
if self.row != other.row:
raise matrix.MatrixSizeError()
M1 = self.copy()
M1.extendColumn(other)
N = M1.kernelAsModule()
if N == None: # zero kernel
N = matrix.zeroMatrix(self.row, 1, self.coeff_ring)
N1 = N.getBlock(1, 1, self.column, N.column) # N.column is dim(ker(M1))
module = Submodule.fromMatrix(self * N1)
module.toHNF()
return module