Adding a "swap" method to equation objects.
Often when working with sage equations, it's desirable to swap the left and right hand side of the equations. (Makes substitutions easier for a start, allows manual solving of inequalities, etc.)
A model implementation by Ivan Andrus https://groups.google.com/forum/#!topic/sagesupport/lKbMSQrFhGg
(in function form) is supplied below (with some rearrangement so equal operator case is tested first):
import operator
def reverse_inequality(eq):
"""
Reverse the order of the inequality without changing it's meaning.
"""
orig_op = eq.operator() # The "toplevel" operator
if orig_op == operator.eq:
op = operator.eq
elif orig_op == operator.lt:
op = operator.gt
elif orig_op == operator.le:
op = operator.ge
elif orig_op == operator.gt:
op = operator.lt
elif orig_op == operator.ge:
op = operator.le
elif orig_op == operator.ne:
op = operator.ne
else:
raise TypeError, "this expression must be a relation"
return op(eq.rhs(), eq.lhs())
My request is that something similar be attached to equation objects as a method.
Change History (7)
Authors: 
→ Ivan Andrus, Joal Heagney

Milestone: 
sage5.11 →
sage5.12

Milestone: 
sage6.1 →
sage6.2

Milestone: 
sage6.2 →
sage6.3

Milestone: 
sage6.3 →
sage6.4

Component: 
algebra →
symbolics

Owner: 
changed from Alex Ghitza to Burcin Erocal

Owner: 
Burcin Erocal deleted
