<A NAME=COMBINELOGS>
<TITLE>COMBINELOGS</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>
<B>COMBINELOGS</B> _ _ _ _ _ _ _ _ _ _ _ _ <B>switch</B><P>
<P>
<P>
<P>
In many cases it is desirable to expand product arguments of logarithms,
or collect a sum of logarithms into a single logarithm. Since these are
inverse operations, it is not possible to provide rules for doing both at
the same time and preserve the REDUCE concept of idempotent evaluation.
As an alternative, REDUCE provides two switches
<A HREF=r37_0285.html>expandlogs</A> and
<em>combinelogs</em> to carry out these operations.
<P> <H3>
examples: </H3>
<P><PRE><TT>
on expandlogs;
log(x*y);
LOG(X) + LOG(Y)
on combinelogs;
ws;
LOG(X*Y)
</TT></PRE><P><P>
<P>
At the present time, it is possible to have both switches on at once,
which could lead to infinite recursion. However, an expression is
switched from one form to the other in this case. Users should not rely
on this behavior, since it may change in the next release.
<P>
<P>
<P>