Corrected contradictions in sparse doc

doc/sandbox/sparse.txt

@@ -19,9 +19,9 @@ Note that you want SciPy >= 0.7.2
 
 We describe the details of the compressed sparse matrix types.
     ``scipy.sparse.csc_matrix``
-        should be used if the columns are sparse.
+        should be used if there are more rows than column (shape[0] > shape[1]).
     ``scipy.sparse.csr_matrix``
-        should be used if the rows are sparse.
+        should be used if there are more columns than rows (shape[0] < shape[1]).
     ``scipy.sparse.lil_matrix``
         is faster if we are modifying the array. After initial inserts,
         we can then convert to the appropriate sparse matrix format.

doc/tutorial/sparse.txt

@@ -80,7 +80,7 @@ the rows and with a matrix that have a lower number of rows, ``csr`` format is a
 
 .. note::
 
-    If shape[0] > shape[1], use ``csr`` format. Otherwise, use ``csc``.
+    If shape[0] > shape[1], use ``csc`` format. Otherwise, use ``csr``.
 
 Sometimes, since the sparse module is young, ops does not exist for both format. So here is
 what may be the most relevent rule: