Sort[]
- To: mathgroup at smc.vnet.net
- Subject: [mg8540] Sort[]
- From: Raya Firsov-Khanin <raya at mech.ed.ac.uk>
- Date: Sat, 6 Sep 1997 23:16:09 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Hello,
I need to Sort[] lists that contain symbols.
I've noticed the following strange feature of Sort[].
Take a simple list
myList = {b, -b}; Sort gives a result in canonical order
Sort[myList]
{-b,b} or
Sort[myList, Less]
{b,-b}
Take now a simple list
myList1 = {-b, b}; Then, Sort gives the same correct result
Sort[myList1]
{-b,b}
while Sort[] with Less argument gives incorrect result.
Sort[myList1, Less]
{-b,b}
Can someone explain what is the problem and how to deal with it?
I also need to work with list where symbols are declared Positive
(or Negative) etc. For instance, declare c Negative:
Sign[c]^=-1;
Then,
Sort[{-c, c}] should give {c, -c}
How to Sort those lists? Is there a way to use Sort[]
or I have to write my own function.
thanks,
Raya Khanin
University of Edinburgh