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<A NAME=FACTOR>

<TITLE>FACTOR</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>FACTOR</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>switch</B><P>
<P>
 
 <P>
<P>
When the <em>factor</em> switch is on, input expressions and results are 
automatically factored. 
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>

on factor; 


aa := 3*x**3*a + 6*x**2*y*a + 3*x**3*b + 6*x**2*y*b

+ x*y*a + 2*y**2*a + x*y*b + 2*y**2*b;
			 


                    2
  AA := (A + B)*(3*X  + Y)*(X + 2*Y) 


off factor; 

aa; 

       3        2                  2         3        2
  3*A*X  + 6*A*X *Y + A*X*Y + 2*A*Y   + 3*B*X  + 6*B*X *Y


+ B*X*Y + 2*B*Y^{2} 

on factor; 

ab := x**2 - 2; 

         2
  AB := X  - 2

</TT></PRE><P>REDUCE factors univariate and multivariate polynomials with 
integer coefficients, finding any factors that also have integer coefficients. 
The factoring is done by reducing multivariate problems to univariate 
ones with symbolic coefficients, and then solving the univariate ones modulo 
small primes. The results of these calculations are merged to 
determine the factors of the original polynomial. The factorizer normally 
selects evaluation points and primes using a random number generator. 
Thus, the detailed factoring behavior may be different each time any 
particular problem is tackled. 
<P>
<P>
When the <em>factor</em> switch is turned on, the 
<A HREF=r37_0256.html>exp</A> switch is 
turned off, and when the <em>factor</em> switch is turned off, the 

<A HREF=r37_0256.html>exp</A> switch is turned on, whether it was on previously 
or not. 
<P>
<P>
When the switch 
<A HREF=r37_0335.html>trfac</A> is on, informative messages are generated at 
each call to the factorizer. The 
<A HREF=r37_0334.html>trallfac</A> switch causes the 
production of a more verbose trace message. It takes precedence over 
<em>trfac</em> if they are both on. 
<P>
<P>
To factor a polynomial explicitly and store the results, use the operator 

<A HREF=r37_0151.html>factorize</A>. 
<P>
<P>
<P>