iterative ref: write tests for iterative_refinement

[geoffwoollard]

Some ideas

• start from simple object:
  • e.g. sphere: No matter how align, the projections will give the right alignment, since they are all the same.
  • have more complicated object, e.g. several constant boxes of ones of length 10-20 in a total size of n_pix=128
  • corrupt initial volume to start with a noisy estimate (e.g. low pass filter by using 3d fft with filter, or add in white noise in 3d)
• generate slices (e.g. 1000)
• call iterative_refinement. Not sure what to pick for sigma, so might want to keep an eye on that.
• check for the following on the returns
  • assert that the half maps are close within some threshold: (half_map_1 * half_map_2).sum()2 / (half_map_12.sum()) * (half_map_2**2).sum()) > 0.99

[geoffwoollard]

I'll write some code snippets to get you started