On branch MCIR_CIL, in SIRF-Exercises/notebooks/MR/, both notebook g_non_cartesian_reconstruction and mr_mcir_grpe call FISTA with the "x_init" argument. In version v22.0.0 of CIL "x_init" has been substituted with "initial", as written here: https://github.com/TomographicImaging/CIL/releases/tag/v22.0.0 . So "x_init" should be replaced with "initial" for the notebooks to work with the newer version of CIL.
On branch MCIR_CIL, in SIRF-Exercises/notebooks/MR/, both notebook g_non_cartesian_reconstruction and mr_mcir_grpe call FISTA with the "x_init" argument. In version v22.0.0 of CIL "x_init" has been substituted with "initial", as written here: https://github.com/TomographicImaging/CIL/releases/tag/v22.0.0 . So "x_init" should be replaced with "initial" for the notebooks to work with the newer version of CIL.