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Add comment about cs matrix multiplication implementation.

This commit is contained in:
sebcrozet 2018-11-06 19:25:27 +01:00
parent f43ab963ad
commit b4b66bddd2
1 changed files with 35 additions and 0 deletions
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35
src/sparse/cs_matrix_ops.rs
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@ -175,6 +175,41 @@ where
} }
} }
// NOTE: the following has a lower complexity, but is slower in many cases, likely because
// of branching inside of the inner loop.
//
// let mut res = CsMatrix::new_uninitialized_generic(nrows1, ncols2, self.len() + rhs.len());
// let mut timestamps = VectorN::zeros_generic(nrows1, U1);
// let mut workspace = unsafe { VectorN::new_uninitialized_generic(nrows1, U1) };
// let mut nz = 0;
//
// for j in 0..ncols2.value() {
// res.data.p[j] = nz;
// let new_size_bound = nz + nrows1.value();
// res.data.i.resize(new_size_bound, 0);
// res.data.vals.resize(new_size_bound, N::zero());
//
// for (i, val) in rhs.data.column_entries(j) {
// nz = self.scatter(
// i,
// val,
// timestamps.as_mut_slice(),
// j + 1,
// workspace.as_mut_slice(),
// nz,
// &mut res,
// );
// }
//
// // Keep the output sorted.
// let range = res.data.p[j]..nz;
// res.data.i[range.clone()].sort();
//
// for p in range {
// res.data.vals[p] = workspace[res.data.i[p]]
// }
// }
res.data.i.truncate(nz); res.data.i.truncate(nz);
res.data.i.shrink_to_fit(); res.data.i.shrink_to_fit();
res.data.vals.truncate(nz); res.data.vals.truncate(nz);