Modulus with Solve
- To: mathgroup at smc.vnet.net
- Subject: [mg38778] Modulus with Solve
- From: Gianluca Gorni <gorni at dimi.uniud.it>
- Date: Sun, 12 Jan 2003 06:16:53 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hello!
Here is a Solve output that is incomplete:
Solve[{n*m == 0, Modulus == 4}, {n, m}]
{{Modulus -> 4, m -> 0}, {Modulus -> 4, n -> 0}}
The solution n=m=2 is missed. I can recover that solution
if I add one more equation:
Solve[{n*m == 0, n == m, Modulus == 4}, {n, m}]
{{Modulus -> 4, n -> 0, m -> 0}, {Modulus -> 4, n -> 2, m -> 2}}
Has all this to do with the familiar fact that Solve can miss
"non-generic" solutions? But then Reduce misses those solutions too.
Perhaps we can't trust results with a nonprime Modulus?
Gianluca Gorni