# libzahl

big integer library
git clone git://git.suckless.org/libzahl

commit a5ae82e67f914d9339ac22e0c2df9fe9b79b0f57
parent 89898de3bfa38d39494555a3e109253489a0e0b6
Author: Mattias Andrée <maandree@kth.se>
Date:   Mon, 25 Jul 2016 17:03:54 +0200

Fix another error in the solution for Powers of the golden ratio

Signed-off-by: Mattias Andrée <maandree@kth.se>

Diffstat:
Mdoc/exercises.tex | 12+++++++-----

1 file changed, 7 insertions(+), 5 deletions(-)
diff --git 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}