SPDHG explicit demo probabilities

[MargaretDuff]

CIL-Demos/demos/2_Iterative/04_SPDHG.ipynb

Line 500 in affca76

"spdhg_explicit = SPDHG(f = F, g = G, operator = K, max_iteration = 5 * 2 * n_subsets,\n",

In the explicit demo for SPDHG you explain the non-uniform sampling: half of the time, we update the dual variable corresponding to TV, so that $p_{n+1}=1/2$, and half of the time we update one of the dual variable corresponding to one subset, so that $p_i=1/(2n)$ for $1\leq i \leq n$.

You also define it in line

CIL-Demos/demos/2_Iterative/04_SPDHG.ipynb

Line 497 in affca76

"prob = [1 / (2 * n_subsets)] * n_subsets + [1 / 2]\n",

but then don't use it in either line

CIL-Demos/demos/2_Iterative/04_SPDHG.ipynb

Line 500 in affca76

"spdhg_explicit = SPDHG(f = F, g = G, operator = K, max_iteration = 5 * 2 * n_subsets,\n",

or line

CIL-Demos/demos/2_Iterative/04_SPDHG.ipynb

Line 581 in affca76

"spdhg_explicit = SPDHG(f = F, g = G, operator = K, max_iteration = 5 * 2 * n_subsets,\n",

.

Just needs a quick fix to add "prob=prob" to the calls to SPDHG.