GPAW’s Matrix object¶
A simple example that we can run with MPI on 4 cores:
from gpaw.matrix import Matrix
from gpaw.mpi import world
a = Matrix(5, 5, dist=(world, 2, 2, 2))
a.array[:] = world.rank
print(world.rank, a.array.shape)
Here, we have created a 5x5 Matrix
of floats distributed on a 2x2
BLACS gris with a blocksize 2 and we then print the shapes of the ndarrays,
which looks like this (in random order):
1 (2, 3)
2 (3, 2)
3 (2, 2)
0 (3, 3)
Let’s create a new matrix b
and redistribute
from
a
to b
:
b = a.new(dist=(None, 1, 1, None))
a.redist(b)
if world.rank == 0:
print(b.array)
This will output:
[[ 0. 0. 2. 2. 0.]
[ 0. 0. 2. 2. 0.]
[ 1. 1. 3. 3. 1.]
[ 1. 1. 3. 3. 1.]
[ 0. 0. 2. 2. 0.]]
Matrixmatrix multiplication
works like this:
from gpaw.matrix import matrix_matrix_multiply as mmm
c = mmm(1.0, a, 'N', a, 'T')
mmm(1.0, a, 'N', a, 'T', 1.0, c, symmetric=True)

gpaw.matrix.
matrix_matrix_multiply
(alpha, a, opa, b, opb, beta=0.0, c=None, symmetric=False)[source]¶ BLASstyle matrixmatrix multiplication.
Will use dgemm/zgemm/dsyrk/zherk/dsyr2k/zher2k as apropriate or the equivalent PBLAS functions for distributed matrices.
The coefficients alpha and beta are of type float. Matrices a, b and c must have same type (float or complex). The strings opa and opb must be ‘N’, ‘T’, or ‘C’ . For opa=’N’ and opb=’N’, the operation performed is equivalent to:
c.array[:] = alpha * np.dot(a.array, b.array) + beta * c.array
Replace a.array with a.array.T or a.array.T.conj() for opa=’T’ and ‘C’ respectively (similarly for opb).
Use symmetric=True if the result matrix is symmetric/hermetian (only lower half of c will be evaluated).

class
gpaw.matrix.
Matrix
(M, N, dtype=None, data=None, dist=None)[source]¶ Matrix object.
 M: int
Rows.
 N: int
Columns.
 dtype: type
Data type (float or complex).
 dist: tuple or None
BLACS distribution given as (communicator, rows, colums, blocksize) tuple. Default is None meaning no distribution.
 data: ndarray or None.
Numpy ndarray to use for starage. By default, a new ndarray will be allocated.

eigh
(cc=False, scalapack=None, 1, 1, None)[source]¶ Calculate eigenvectors and eigenvalues.
Matrix must be symmetric/hermitian and stored in lower half.
 cc: bool
Complex conjugate matrix before finding eigenvalues.
 scalapack: tuple
BLACS distribution for ScaLapack to use. Default is to do serial diagonalization.

multiply
(alpha, opa, b, opb, beta=0.0, out=None, symmetric=False)[source]¶ BLASstyle Matrixmatrix multiplication.
See matrix_matrix_multipliction() for details.