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170 lines
3.2 KiB
170 lines
3.2 KiB
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<!-- Created by texi2html 1.56k from cln.texi on 19 May 2000 -->
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<TITLE>CLN, a Class Library for Numbers - 1. Introduction</TITLE>
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Go to the first, previous, <A HREF="cln_2.html">next</A>, <A HREF="cln_13.html">last</A> section, <A HREF="cln_toc.html">table of contents</A>.
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<P><HR><P>
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<H1><A NAME="SEC1" HREF="cln_toc.html#TOC1">1. Introduction</A></H1>
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<P>
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CLN is a library for computations with all kinds of numbers.
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It has a rich set of number classes:
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<UL>
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<LI>
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Integers (with unlimited precision),
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<LI>
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Rational numbers,
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<LI>
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Floating-point numbers:
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<UL>
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<LI>
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Short float,
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<LI>
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Single float,
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<LI>
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Double float,
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<LI>
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Long float (with unlimited precision),
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</UL>
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<LI>
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Complex numbers,
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<LI>
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Modular integers (integers modulo a fixed integer),
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<LI>
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Univariate polynomials.
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</UL>
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<P>
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The subtypes of the complex numbers among these are exactly the
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types of numbers known to the Common Lisp language. Therefore
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<CODE>CLN</CODE> can be used for Common Lisp implementations, giving
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<SAMP>`CLN'</SAMP> another meaning: it becomes an abbreviation of
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"Common Lisp Numbers".
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<P>
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The CLN package implements
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<UL>
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<LI>
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Elementary functions (<CODE>+</CODE>, <CODE>-</CODE>, <CODE>*</CODE>, <CODE>/</CODE>, <CODE>sqrt</CODE>,
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comparisons, ...),
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<LI>
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Logical functions (logical <CODE>and</CODE>, <CODE>or</CODE>, <CODE>not</CODE>, ...),
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<LI>
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Transcendental functions (exponential, logarithmic, trigonometric, hyperbolic
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functions and their inverse functions).
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</UL>
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<P>
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CLN is a C++ library. Using C++ as an implementation language provides
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<UL>
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<LI>
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efficiency: it compiles to machine code,
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<LI>
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type safety: the C++ compiler knows about the number types and complains
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if, for example, you try to assign a float to an integer variable.
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<LI>
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algebraic syntax: You can use the <CODE>+</CODE>, <CODE>-</CODE>, <CODE>*</CODE>, <CODE>=</CODE>,
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<CODE>==</CODE>, ... operators as in C or C++.
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</UL>
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<P>
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CLN is memory efficient:
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<UL>
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<LI>
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Small integers and short floats are immediate, not heap allocated.
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<LI>
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Heap-allocated memory is reclaimed through an automatic, non-interruptive
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garbage collection.
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</UL>
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<P>
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CLN is speed efficient:
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<UL>
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<LI>
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The kernel of CLN has been written in assembly language for some CPUs
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(<CODE>i386</CODE>, <CODE>m68k</CODE>, <CODE>sparc</CODE>, <CODE>mips</CODE>, <CODE>arm</CODE>).
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<LI>
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<A NAME="IDX1"></A>
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On all CPUs, CLN may be configured to use the superefficient low-level
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routines from GNU GMP version 3.
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<LI>
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It uses Karatsuba multiplication, which is significantly faster
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for large numbers than the standard multiplication algorithm.
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<LI>
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For very large numbers (more than 12000 decimal digits), it uses
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Schönhage-Strassen
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<A NAME="IDX2"></A>
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multiplication, which is an asymptotically optimal multiplication
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algorithm, for multiplication, division and radix conversion.
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</UL>
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<P>
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CLN aims at being easily integrated into larger software packages:
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<UL>
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<LI>
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The garbage collection imposes no burden on the main application.
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<LI>
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The library provides hooks for memory allocation and exceptions.
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</UL>
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<P><HR><P>
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Go to the first, previous, <A HREF="cln_2.html">next</A>, <A HREF="cln_13.html">last</A> section, <A HREF="cln_toc.html">table of contents</A>.
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