Xform for a constant scaling or shifting

[junchaoxia]

The implementations of Multiply and Shift Xfrom classes need to take an ndarray as input. This assumes each image has different values of scaling and shifting. It will be better if we also have an option to take only a scalar when the values are the same for all images, such as the case below:

https://github.com/ComputationalCryoEM/ASPIRE-Python/blob/preprocess/src/aspire/source/__init__.py#L431

[janden]

Agreed. To be clear, we're not talking about a new Xform, just making Multiply and Shift take a scalar input, correct?

[junchaoxia]

Yes. We can avoid creating new classes by the size of input values of scaling and shifting.

[junchaoxia]

This issue has been addressed in PR #253. Closing now.