REF: Change initial step sizes for line search

[carterbox]

Purpose

Decrease the time spend line searching with minimal effort. Related to #61, #60 .

Approach

Adjusted the initial step sizes for the ptychography solver according to my observations from two real datasets. While the probe step size seems to remain on the order of 1, the object step size consistently shrinks to the order of 1e-5. I guessed that this was related the scan area.

My observation is that applying the smaller initial step for the object update decreases times per epoch by an order of magnitude.

Pre-Merge Checklists

Submitter

• [x] Write a helpfully descriptive pull request title.
• [x] Organize changes into logically grouped commits with descriptive commit messages.
• [x] Document all new functions.
• [x] Write tests for new functions or explain why they are not needed.
• [ ] Build the documentation successfully
• [x] Use yapf to format python code.

Reviewer

• [ ] Actually read all of the code.
• [ ] Run the new code yourself.
• [ ] Write a summary of the changes as you understand them.
• [ ] Thank the submitter.

[pep8speaks]

Hello @carterbox! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers:

Comment last updated at 2020-08-14 19:45:27 UTC