Following up on the recent thread "coercion error: calling functions
with vector inputs", I am trying to get SR(vector([1,2,])) to work.
In symbolic/ring.pyx, we have in the _element_constructor_ function,
line 269 or so, the default case:
elif isinstance(x, RingElement):
GEx_construct_pyobject(exp, x)
so that explains why SR(matrix([[1,2]])) works. However,
isinstance(vector([1,2]), RingElement) is False, so a vector falls
through to the type error. What is the reason for insisting that the
thing must be a RingElement (as opposed to, say, an Element)?
I've pasted below a patch to make SR(vector([1,2])) work. However, I'm
not sure that this is the right thing to do, compared to maybe making
vectors really be pynac objects, rather than just wrapped python objects.
However, with this patch, this works:
sage: var('t')
t
sage: r=vector([cos(t),t^2])
sage: s=vector([sin(t),t])
sage: f(x,y)=x+2*y
sage: f(SR(r),SR(s))
(2*sin(t) + cos(t), t^2 + 2*t)
sage: f(r,s)
Coercion error
Thanks,
Jason
--
Jason Grout
diff -r 856e914baa43 sage/symbolic/ring.pyx
--- a/sage/symbolic/ring.pyx Tue Oct 27 19:53:07 2009 -0500
+++ b/sage/symbolic/ring.pyx Tue Oct 27 21:08:55 2009 -0500
@@ -26,6 +26,7 @@
from sage.symbolic.expression import is_Expression
from sage.structure.element cimport RingElement, Element
+from sage.structure.element import is_Vector
from sage.structure.parent_base import ParentWithBase
from sage.rings.ring cimport CommutativeRing
from sage.categories.morphism cimport Morphism
@@ -193,6 +194,13 @@
sage: SR(complex(2,-3))
2.00000000000000 - 3.00000000000000*I
+ A vector::
+
+ sage: a=SR(vector([1,2]))
+ sage: t=var('t')
+ sage: b=SR(vector([t,t^2]))
+ sage: a+2*b
+
TESTS::
sage: SR._coerce_(int(5))
@@ -266,7 +274,7 @@
return new_Expression_from_GEx(self, g_mInfinity)
elif x is unsigned_infinity:
return new_Expression_from_GEx(self, g_UnsignedInfinity)
- elif isinstance(x, RingElement):
+ elif isinstance(x, RingElement) or is_Vector(x):
GEx_construct_pyobject(exp, x)
else:
raise TypeError
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