[Nils Bruin]

The documentation of "at" says that "substitutions are made in series, not in parallel". However (thankfully) that does not seem to be the case:
(%i1) at(f(x,y),[x=x+y,y=x-y]);
(%o1) f(y + x, x - y)
(%i2) at(at(f(x,y),x=x+y),y=x-y);
(%o2) f(2 x - y, x - y)
(%i3) at(at(f(x,y),y=x-y),x=x+y);
(%o3) f(y + x, x)
Clearly, this is the desired behaviour, but it's at odds with the documentation. Perhaps adjust the documentation?

Fixed in Expressions.texi revision 1.72
Closing this bug report as fixed.
Dieter Kaiser

• status: open --> closed