BF: fix Python 2, old Sympy stuff in derivations

Python 2 prints, and older uses of Sympy.

Author: matthew-brett

doc/source/dicom/derivations/dicom_mosaic.py

@@ -1,11 +1,13 @@
 ''' Just showing the mosaic simplification '''
-import sympy
-from sympy import Matrix, Symbol, symbols, zeros, ones, eye
+
+from sympy import Matrix, Symbol, symbols, simplify
+
 
 def numbered_matrix(nrows, ncols, symbol_prefix):
     return Matrix(nrows, ncols, lambda i, j: Symbol(
             symbol_prefix + '_{%d%d}' % (i+1, j+1)))
 
+
 def numbered_vector(nrows, symbol_prefix):
     return Matrix(nrows, 1, lambda i, j: Symbol(
             symbol_prefix + '_{%d}' % (i+1)))
@@ -14,7 +16,7 @@ def numbered_vector(nrows, symbol_prefix):
 RS = numbered_matrix(3, 3, 'rs')
 
 mdc, mdr, rdc, rdr = symbols(
-    'md_{cols}', 'md_{rows}', 'rd_{cols}', 'rd_{rows}')
+    'md_{cols} md_{rows} rd_{cols} rd_{rows}')
 
 md_adj = Matrix((mdc - 1, mdr - 1, 0)) / -2
 rd_adj = Matrix((rdc - 1 , rdr - 1, 0)) / -2
@@ -25,6 +27,5 @@ def numbered_vector(nrows, symbol_prefix):
 Q = RS[:,:2] * Matrix((
         (mdc - rdc) / 2,
         (mdr - rdr) / 2))
-Q.simplify()
 
-assert adj == Q
+assert simplify(adj - Q) == Matrix([0, 0, 0])

doc/source/dicom/derivations/spm_dicom_orient.py

@@ -3,24 +3,27 @@
 Notes on the SPM orientation machinery.
 
 There are symbolic versions of the code in ``spm_dicom_convert``,
-``write_volume`` subfunction, around line 509 in the version I have
-(SPM8, late 2009 vintage).
+``write_volume`` subfunction, around line 509 in the version I have (SPM8, late
+2009 vintage).
 '''
 
 import numpy as np
 
 import sympy
 from sympy import Matrix, Symbol, symbols, zeros, ones, eye
 
+
 # The code below is general (independent of SPMs code)
 def numbered_matrix(nrows, ncols, symbol_prefix):
     return Matrix(nrows, ncols, lambda i, j: Symbol(
             symbol_prefix + '_{%d%d}' % (i+1, j+1)))
 
+
 def numbered_vector(nrows, symbol_prefix):
     return Matrix(nrows, 1, lambda i, j: Symbol(
             symbol_prefix + '_{%d}' % (i+1)))
 
+
 # premultiplication matrix to go from 0 based to 1 based indexing
 one_based = eye(4)
 one_based[:3,3] = (1,1,1)