diff options
Diffstat (limited to 'gr-fec/python/fec/LDPC/Generate_LDPC_matrix_functions.py')
| -rw-r--r-- | gr-fec/python/fec/LDPC/Generate_LDPC_matrix_functions.py | 49 |
1 files changed, 47 insertions, 2 deletions
diff --git a/gr-fec/python/fec/LDPC/Generate_LDPC_matrix_functions.py b/gr-fec/python/fec/LDPC/Generate_LDPC_matrix_functions.py index 85f8ce9759..5e92bd0900 100644 --- a/gr-fec/python/fec/LDPC/Generate_LDPC_matrix_functions.py +++ b/gr-fec/python/fec/LDPC/Generate_LDPC_matrix_functions.py @@ -26,7 +26,7 @@ from numpy.random import shuffle, randint from numpy.linalg import inv, det # 0 gives no debug output, 1 gives a little, 2 gives a lot -verbose = 0 +verbose = 1 ####################################################### class LDPC_matrix: """ Class for a LDPC parity check matrix """ @@ -420,7 +420,6 @@ def greedy_upper_triangulation(H): # version of H that has a nonsingular phi. if verbose: print '--- Error: nonsingular phi matrix not found.' - def inv_mod2(squareMatrix): """ Calculates the mod 2 inverse of a matrix. @@ -617,3 +616,49 @@ def get_best_matrix(H,numIterations=100): print 'Error: Could not find appropriate H form', print 'for encoding.' return + +def getSystematicGmatrix(H): + """ + This function finds the systematic form of the generator + matrix G. The form is G = [I P] where I is an identity matrix + and P is the parity submatrix. If the H matrix provided + is not full rank, then dependent rows will be deleted. + """ + tempArray = H.copy() + numRows = tempArray.shape[0] + numColumns = tempArray.shape[1] + limit = numRows + rank = 0 + i = 0 + while i < limit: + # Flag indicating that the row contains a non-zero entry + found = False + for j in arange(i, numColumns): + if tempArray[i, j] == 1: + # Encountered a non-zero entry at (i, j) + found = True + # Increment rank by 1 + rank = rank + 1 + # make the entry at (i,i) be 1 + tempArray = swap_columns(j,i,tempArray) + break + if found == True: + for k in arange(0,numRows): + if k == i: continue + # Checking for 1's + if tempArray[k, i] == 1: + # add row i to row k + tempArray[k,:] = tempArray[k,:] + tempArray[i,:] + # Addition is mod2 + tempArray = tempArray.copy() % 2 + # All the entries above & below (i, i) are now 0 + i = i + 1 + if found == False: + # push the row of 0s to the bottom, and move the bottom + # rows up (sort of a rotation thing) + tempArray = moveRowToBottom(i,tempArray) + # decrease limit since we just found a row of 0s + limit -= 1 + # the rows below i are the dependent rows, which we discard + G = tempArray[0:i,:] + return G
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