eja: don't mess with the user's basis.

[sage.d.git] / mjo / eja / eja_utils.py

diff --git a/mjo/eja/eja_utils.py b/mjo/eja/eja_utils.py
index 81b5634bc921736b0d007f3df04013d0dc6df265..832dcef1fac0baa573b4883bc4e2ddd3fbfd55a8 100644 (file)
--- a/mjo/eja/eja_utils.py
+++ b/mjo/eja/eja_utils.py
@@ -2,57 +2,6 @@ from sage.functions.other import sqrt
 from sage.matrix.constructor import matrix
 from sage.modules.free_module_element import vector
 
-def _change_ring(x, R):
-    r"""
-    Change the ring of a vector, matrix, or a cartesian product of
-    those things.
-
-    SETUP::
-
-        sage: from mjo.eja.eja_utils import _change_ring
-
-    EXAMPLES::
-
-        sage: v = vector(QQ, (1,2,3))
-        sage: m = matrix(QQ, [[1,2],[3,4]])
-        sage: _change_ring(v, RDF)
-        (1.0, 2.0, 3.0)
-        sage: _change_ring(m, RDF)
-        [1.0 2.0]
-        [3.0 4.0]
-        sage: _change_ring((v,m), RDF)
-        (
-                         [1.0 2.0]
-        (1.0, 2.0, 3.0), [3.0 4.0]
-        )
-        sage: V1 = cartesian_product([v.parent(), v.parent()])
-        sage: V = cartesian_product([v.parent(), V1])
-        sage: V((v, (v, v)))
-        ((1, 2, 3), ((1, 2, 3), (1, 2, 3)))
-        sage: _change_ring(V((v, (v, v))), RDF)
-        ((1.0, 2.0, 3.0), ((1.0, 2.0, 3.0), (1.0, 2.0, 3.0)))
-
-    """
-    try:
-        return x.change_ring(R)
-    except AttributeError:
-        try:
-            from sage.categories.sets_cat import cartesian_product
-            if hasattr(x, 'element_class'):
-                # x is a parent and we're in a recursive call.
-                return cartesian_product( [_change_ring(x_i, R)
-                                           for x_i in x.cartesian_factors()] )
-            else:
-                # x is an element, and we want to change the ring
-                # of its parent.
-                P = x.parent()
-                Q = cartesian_product( [_change_ring(P_i, R)
-                                        for P_i in P.cartesian_factors()] )
-                return Q(x)
-        except AttributeError:
-            # No parent for x
-            return x.__class__( _change_ring(x_i, R) for x_i in x )
-
 def _scale(x, alpha):
     r"""
     Scale the vector, matrix, or cartesian-product-of-those-things