Merge branch 'master' into leastsquares-doc

Signed-off-by: Margaret Duff <43645617+MargaretDuff@users.noreply.github.com>

CHANGELOG.md

@@ -3,6 +3,8 @@
   - Allow reduction methods on the DataContainer class to accept axis argument as string which matches values in dimension_labels
   - Added the functions `set_norms` and `get_norms` to the `BlockOperator` class
   - Fixed formatting errors in the L2NormSquared and LeastSquares documentation 
+  - Internal variable name change in BlockOperator to aid understanding 
+
 
 * 23.1.0
   - Fix bug in IndicatorBox proximal_conjugate

Wrappers/Python/cil/optimisation/operators/BlockOperator.py

@@ -212,17 +212,18 @@ def direct(self, x, out=None):
 
             tmp = self.range_geometry().allocate()
             for row in range(self.shape[0]):
-                for col in range(self.shape[1]):
-                    if col == 0:
-                        self.get_item(row, col).direct(
-                            x_b.get_item(col),
-                            out=out.get_item(row))
+                for col in range(self.shape[1]):  
+                    if col == 0:       
+                        self.get_item(row,col).direct(
+                                                      x_b.get_item(col),
+                                                      out=out.get_item(row))                        
                     else:
-                        a = out.get_item(row)
-                        self.get_item(row, col).direct(
-                            x_b.get_item(col),
-                            out=tmp.get_item(row))
-                        a += tmp.get_item(row)
+                        temp_out_row = out.get_item(row) # temp_out_row points to the element in out that we are adding to  
+                        self.get_item(row,col).direct(
+                                                      x_b.get_item(col), 
+                                                      out=tmp.get_item(row))
+                        temp_out_row += tmp.get_item(row)
+
 
     def adjoint(self, x, out=None):
         '''Adjoint operation for the BlockOperator
@@ -282,10 +283,11 @@ def adjoint(self, x, out=None):
                             out += self.get_item(row, col).adjoint(
                                 x_b.get_item(row))
                         else:
-                            a = out.get_item(col)
-                            a += self.get_item(row, col).adjoint(
-                                x_b.get_item(row),
-                            )
+
+                            temp_out_col = out.get_item(col) # out_col_operator points to the column in out that we are updating 
+                            temp_out_col += self.get_item(row,col).adjoint(
+                                                        x_b.get_item(row),
+                                                        )
 
     def is_linear(self):
         '''Returns whether all the elements of the BlockOperator are linear'''