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

[sage.d.git] / mjo / eja / DESIGN

diff --git a/mjo/eja/DESIGN b/mjo/eja/DESIGN
index 7607b1ceffeddabb19687a9da54e362b07c9d5f3..75302ca0f9ba4323ac634834f4be816aa8866010 100644 (file)
--- a/mjo/eja/DESIGN
+++ b/mjo/eja/DESIGN
@@ -81,6 +81,14 @@ the same way as the octonion algebra, but for the sake of the user
 interface, we must also support at least the usual SageMath vectors
 and matrices.
 
 interface, we must also support at least the usual SageMath vectors
 and matrices.
 

+Note: this has one less-than-obvious consequence: we have to assume
+that the user has supplied an entirely-correct basis (with entries in
+the correct structure). We generally cannot mess witht the entries of
+his basis, or use them to figure out what (for example) the ambient
+scalar ring is. None of these are insurmountable obstacles; we just
+have to be a little careful distinguishing between what's inside the
+algebra elements and what's outside them.
+

 Basis normalization
 -------------------
 For performance reasons, we prefer the algebra constructors to
 Basis normalization
 -------------------
 For performance reasons, we prefer the algebra constructors to