Qiskit / qiskit / 11613373021

88%

Build Type

push

github

Committed by web-flow

Commit Message

Optimise `SparsePauliOp.from_operator` (#11557)

* Optimise `SparsePauliOp.from_operator`

This rewrites the `from_operator` handling (again!) from the initial
Rust implementation of the recursive matrix-addition form into an
iterative approach that re-uses the same scratch memory all the way
down.  This is significantly faster, and allocates far less often,
although in practice the peak heap memory usage will be not dissimilar.

The algorithm is rewritten to be a manual stack-based iteration, rather
than a functional recursion.  The size of a single stack entry in the
iteration is one `usize`, which is drastically smaller than whatever
per-function-call stack will have been used before.

* Improve documentation

* Increase test coverage

Run Details

316 of 338 new or added lines in 1 file covered. (93.49%)

27 existing lines in 2 files now uncovered.

75943 of 85592 relevant lines covered (88.73%)

360489.33 hits per line