# libzahl

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

commit d89b4e54d7b4ee8aee05051ccf6e3b96019ac3ea
parent dbb82e8a1184eaa7f6fa4b04e0560589cc6092e9
Author: Mattias Andrée <maandree@kth.se>
Date:   Sun, 24 Jul 2016 18:04:15 +0200

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

Diffstat:
Mdoc/exercises.tex | 32+++++++++++++++++++++++++++++++-

1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/doc/exercises.tex b/doc/exercises.tex
@@ -22,6 +22,22 @@
\begin{enumerate}[label=\textbf{\arabic*}.]

+
+\item {[$\RHD$\textit{02}]} \textbf{Saturated subtraction}
+
+Implement the function
+
+\vspace{-1em}
+\begin{alltt}
+   void monus(z_t r, z_t a, z_t b);
+\end{alltt}
+\vspace{-1em}
+
+\noindent
+which calculates $a \dotminus b = \max \{ 0,~ a - b \}$.
+
+
+
\item {[\textit{M10}]} \textbf{Convergence of the Lucas Number ratios}

Find an approximation for
@@ -122,6 +138,20 @@ Use this to implement a fast primality tester.

\begin{enumerate}[label=\textbf{\arabic*}.]

+\item \textbf{Saturated subtraction}
+
+\vspace{-1em}
+\begin{alltt}
+void monus(z_t r, z_t a, z_t b)
+\{
+    zsub(r, a, b);
+    if (zsignum(r) < 0)
+        zsetu(r, 0);
+\}
+\end{alltt}
+
+
+
\item \textbf{Convergence of the Lucas Number ratios}

It would be a mistake to use bignum, and bigint in particular,
@@ -243,7 +273,7 @@ enum zprimality ptest_fast(z_t p)
z_t a;
int c = zcmpu(p, 2);
if (c <= 0)
-      return c ? NONPRIME : PRIME;
+        return c ? NONPRIME : PRIME;
zinit(a);
zsetu(a, 1);
zlsh(a, a, p);