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Problem 6:  Revised specification.

Write and test a program to meet this specification:
\begin{verbatim}
/*===========================================================================
			 n <-- RLOG2(R,k)

Rational number logarithm, base 2.

Inputs
  R : a positive rational number,
  k : a positive BETA-digit.

Output
  n : an integer such that | L - n/2^k | < 1/2^k.

===========================================================================*/
#include "saclib.h"

Word RLOG2(R,k)
       Word R,k;
{
	Word n;
   ///
}
\end{verbatim}

Hint;\\
Note that the integer part, $m$, of $\log_2 (R)$ can be computed
by use of \verb|ILOG2()|.  Then $1 \leq R/2^m < 2$.  Let $S = R/2^k$.  
It suffices to compute successive bits of $l = \log_2 (S)$.
Notice that the first bit of $l$ will be 1 just in case $S^2 \geq 2$.
By adjusting and repeated squaring, additional bits may be determined
similarly.

Try your program for several values of $k$.  What do your experiments
suggest about the efficiency of the algorithm?  Give a brief
report and discussion.

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