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.
 
+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