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-rw-r--r--doc/exercises.tex12
1 files changed, 7 insertions, 5 deletions
diff --git a/doc/exercises.tex b/doc/exercises.tex
index 93f77e4..160067d 100644
--- a/doc/exercises.tex
+++ b/doc/exercises.tex
@@ -488,7 +488,7 @@ the set of pseudoprimes.
\item \textbf{Powers of the golden ratio}
This was an information gathering exercise.
-For $n \ge 1$, $L_n = [\varphi^n]$, where
+For $n \ge 2$, $L_n = [\varphi^n]$, where
$L_n$ is the $n^\text{th}$ Lucas number.
\( \displaystyle{
@@ -505,12 +505,14 @@ but for efficiency and briefness, we will use
\vspace{-1em}
\begin{alltt}
-void golden_pow(z_t r, z_t p)
+void golden_pow(z_t r, z_t n)
\{
- if (zsignum(p) <= 0)
- zsetu(r, zcmpi(p, -1) >= 0);
+ if (zsignum(n) <= 0)
+ zsetu(r, zcmpi(n, -1) >= 0);
+ else if (!zcmpu(n, 1))
+ zsetu(r, 2);
else
- lucas(r, p);
+ lucas(r, n);
\}
\end{alltt}