Srtanh

[yyang606]

Please review the developer documentation
on the wiki of this project that contains help and requirements.

Proposed changes

Describe what this PR changes and why. If it closes an issue, link to it here
with a supported keyword.

What type(s) of changes does this code introduce?

Delete the items that do not apply

• Other (please describe): made the number of positive and negative terms in the sum of images expression equal to facilitate convergence.

Does this introduce a breaking change?

• No

What systems has this change been tested on?

Checklist

Update the following with a yes where the items apply. If you're unsure about any of them, don't hesitate to ask. This is
simply a reminder of what we are going to look for before merging your code.

• No. This PR is up to date with current the current state of 'develop'
• Yes/No. Code added or changed in the PR has been clang-formatted
• No. This PR adds tests to cover any new code, or to catch a bug that is being fixed
• No. Documentation has been added (if appropriate)

[yyang606]

Made the number of positive and negative terms in the sum of images expression equal to facilitate convergence.

[Paul-St-Young]

This PR is made on top of an old commit.
@yyang606 Please first pull all changes from the mch branch and then make your change to Screen2D.cpp.
The "Files Changed" tab should contain only a single file.