Margaret Duff

Thanks Gemma - have added this comment to #1644 PR which attempted to fix the slow tests

Closed by #1898

> Checked on the CIL demo notebooks and hasn't broken any backward compatibility there > > - [ ] [binder](https://github.com/TomographicImaging/CIL-Demos/tree/main/binder) > - [x] [colab](https://github.com/TomographicImaging/CIL-Demos/tree/main/colab) > - [x] [demos/1_Introduction](https://github.com/TomographicImaging/CIL-Demos/tree/main/demos/1_Introduction) > -...

Have run a few of the iterative (folder 2) demo notebooks and all is fine there

@epapoutsellis - if you have a moment, please can you sense check this for me?

Thanks @epapoutsellis some initial thoughts but I can take another look next week - > * PDHG with `verbose=2` does not print primal-dual gap as before A callback to print...

I had a bit of a play and got it to show:    Not a fix to doing the factory methods automatically but one way of explaining it...

For reference: PDHG parameters: - f ([Function](https://tomographicimaging.github.io/CIL/nightly/optimisation.html#cil.optimisation.functions.Function)) – A convex function with a “simple” proximal method of its conjugate. - g ([Function](https://tomographicimaging.github.io/CIL/nightly/optimisation.html#cil.optimisation.functions.Function)) – A convex function with a “simple” proximal....

See also Gemma's comment https://github.com/TomographicImaging/CIL/issues/1496#issuecomment-2039494809

I am struggling with a test which compares PDHG and SPDHG where the number of subsets is one: #1863