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from scipy.sparse import coo_matrix
import struct
import numpy as np
def load(fname):
MATRIX_MAGIC = 1211216
VECTOR_MAGIC = 1211214
with open(fname, "rb") as f:
magic = struct.unpack(">i", f.read(4))[0]
if magic == MATRIX_MAGIC:
m = struct.unpack(">i", f.read(4))[0]
n = struct.unpack(">i", f.read(4))[0]
nonzero = struct.unpack(">i", f.read(4))[0]
nonzero_row = struct.unpack(">%di" %(m), f.read(m*4))
ks = struct.unpack(">%di" %(nonzero), f.read(nonzero*4))
xs = np.array(struct.unpack(">%dd" %(nonzero), f.read(nonzero*8)))
ii = np.zeros(nonzero, dtype=int)
jj = np.zeros(nonzero, dtype=int)
a = 0
for i in range(0, m):
for j in range(0, nonzero_row[i]):
ii[a] = i
jj[a] = ks[a]
a += 1
return coo_matrix((xs, (ii, jj)), shape=(m, n))
elif magic == VECTOR_MAGIC:
m = struct.unpack(">i", f.read(4))[0]
xs = np.array(struct.unpack(">%dd" %(m), f.read(m*8)))
return xs
else:
sys.stderr.write("Incorrect PETSc magic number (read %d).\n" %(magic))
exit(1)
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