# Finding a Sign of a Polynomial

## What is "FindSign"?

We know that x^2-2xy+y^2 is nonnegative if x and y are real variables, since it is
equal to (x-y)^2. Furthermore, when we know beforehand that a is positive, x^2-2xy+y^2+a
is positive. FindSign gives you the sign of a polynomial of several variables and
parameters, all of which are in real domain.

"FindSign.m" is a Mathematica package for determing signs, and
"FindSign.exe" is a front-end program for an easy-to-use manipulation.

After starting FindSign.exe, you will see

Type an expression in the "Expression" box. Type variables of which signs are
known in the corresponding box of the "Sign-Known Varialbes." Press the
"Evaluate" button and you get the answer in the "Output:Sign" box.
Pressing the "See Structure" gives you the information of a polynomial as:

It is easy, isn't it?

## Installation

- Download these files:
- Put FindSign.exe, FinsSign.hlp and FindSign.m in a searchable directory. The Mathemaica
home directory is a good place for a trial.

Go to Home Page.

Yuji Itaya: itaya@alice.asahi-u.ac.jp