commit 813c362c7e1bbcc503d2bf62275bd304d0943d44
parent 206a31938de2ac7e31008caf32a0f9e8a4c212ce
Author: Mattias Andrée <maandree@kth.se>
Date: Mon, 9 May 2016 19:47:10 +0200
Some comments
Signed-off-by: Mattias Andrée <maandree@kth.se>
Diffstat:
2 files changed, 36 insertions(+), 8 deletions(-)
diff --git a/doc/get-started.tex b/doc/get-started.tex
@@ -8,6 +8,9 @@ You should read the sections in order.
\minitoc
+% TODO add a section a linking and stuff here.
+
+
\newpage
\section{Initialisation}
\label{sec:Initialisation}
diff --git a/doc/what-is-libzahl.tex b/doc/what-is-libzahl.tex
@@ -44,7 +44,7 @@ number types than integers. libzahl only supports integers.
\label{sec:Why does it exist?}
libzahl's main competitors are GNU MP (gmp),\footnote{GNU
-Multiple Precision Arithmetic Library} LibTomMath (ltm),
+Multiple Precision Arithmetic Library} LibTomMath (ltm),
TomsFastMath (tfm) and Hebimath. All of these have problems:
\begin{itemize}
@@ -65,12 +65,6 @@ this, it is not really that simple.
TomsFastMath is slow, complicated, and is not a true
big integer library and is specifically targeted at
cryptography.
-
-\item
-Hebimath is far from stable, some fundamental functions
-are not implemented and some functions are broken. The
-author thinks Hebimath is promising, but that many things
-can be done better.
\end{itemize}
libzahl is developed under the suckless.org umbrella.
@@ -82,6 +76,18 @@ applications. Currently however, it does not support
multithreading, but it has better support multiprocessing
and distributed computing than its competitor.
+Lesser ``competitors'' to libzahl include Hebimath and
+bsdnt.
+
+\begin{itemize}
+\item
+Hebimath is far from stable, some fundamental functions
+are not implemented and some functions are broken. The
+author of libzahl thinks Hebimath is promising, but that
+it could be better designed. Like libzahl, Hebimath aims
+to follow the suckless philosophy.
+\end{itemize}
+
\newpage
\section{How is it different?}
@@ -136,7 +142,26 @@ occur, not also after each function-return.
Additionally, libzahl tries to keep the functions'
names simple and natural rather than techniqual or
mathematical. The names resemble those of the standard
-integer operators.
+integer operators. For example, the left-shift, right-shift
+and truncation bit-operations in libzahl is called
+{\tt zlsh}, {\tt zrsh} and {\tt ztrunc}, respectively.
+In GNU MP, they are called {\tt mpz\_mul\_2exp},
+{\tt mpz\_tdiv\_q\_2exp} and {\tt mpz\_tdiv\_r\_2exp}.
+The need of complicated names are diminished by resisting
+to implement all possible variants of each operations.
+Variants of a function simply append a short description
+of the difference in plain text. For example, a variant of
+{\tt zadd} that makes the assumption that both operands
+are non-negative (or if not so, calculates the sum of
+their absolute values) is called {\tt zadd\_unsigned}.
+If libzahl would have had floored and ceiled variants of
+{\tt zdiv} (truncated division), they would have been
+called {\tt zdiv\_floor} and {\tt zdiv\_ceiling}.
+{\tt zdiv} and {\tt zmod} (modulus) are variants of
+{\tt zdivmod} that throw away one of the outputs. These
+names can be compared to GNU MP's variants of truncated
+division: {\tt mpz\_tdiv\_q}, {\tt mpz\_tdiv\_r} and
+{\tt mpz\_tdiv\_qr}.
\newpage
