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diff --git a/libstdc++-v3/docs/html/26_numerics/howto.html b/libstdc++-v3/docs/html/26_numerics/howto.html new file mode 100644 index 00000000000..c69532dbfcd --- /dev/null +++ b/libstdc++-v3/docs/html/26_numerics/howto.html @@ -0,0 +1,142 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"> +<HTML> +<HEAD> + <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> + <META NAME="AUTHOR" CONTENT="pme@sources.redhat.com (Phil Edwards)"> + <META NAME="KEYWORDS" CONTENT="HOWTO, libstdc++, GCC, g++, libg++, STL"> + <META NAME="DESCRIPTION" CONTENT="HOWTO for the libstdc++ chapter 26."> + <META NAME="GENERATOR" CONTENT="vi and eight fingers"> + <TITLE>libstdc++-v3 HOWTO: Chapter 26</TITLE> +<LINK REL=StyleSheet HREF="../lib3styles.css"> +<!-- $Id: howto.html,v 1.7 2000/12/03 23:47:48 jsm28 Exp $ --> +</HEAD> +<BODY> + +<H1 CLASS="centered"><A NAME="top">Chapter 26: Numerics</A></H1> + +<P>Chapter 26 deals with building block abstractions to aid in + numerical computing: + <UL> + <LI>Template data structures such as <TT>valarray<></TT> + and <TT>complex<></TT>. + <LI>Template numerical functions such as <TT>accumulate</TT>; + <TT>inner_product</TT>; <TT>partial_sum</TT> and + <TT>adjacent_difference</TT>. + </UL> + All of the Standard C math functions are of course included in C++, + and overloaded versions for <TT>long</TT>, <TT>float</TT>, and + <TT>long double</TT> have been added for all of them. +</P> + +<!-- ####################################################### --> +<HR> +<H1>Contents</H1> +<UL> + <LI><A HREF="#1">Complex Number Processing</A> + <LI><A HREF="#2">Array Processing</A> + <LI><A HREF="#3">Numerical Functions</A> +</UL> + +<HR> + +<!-- ####################################################### --> + +<H2><A NAME="1">Complex Number Processing</A></H2> + <P>Using <TT>complex<></TT> becomes even more comple- er, sorry, + <EM>complicated</EM>, with the not-quite-gratuitously-incompatible + addition of complex types to the C language. David Tribble has + compiled a list of C++98 and C99 conflict points; his description of + C's new type versus those of C++ and how to get them playing together + nicely is +<A HREF="http://home.flash.net/~dtribble/text/cdiffs.htm#C99.complex">here</A>. + </P> + <P><TT>complex<></TT> is intended to be instantiated with a + floating-point type. As long as you meet that and some other basic + requirements, then the resulting instantiation has all of the usual + math operators defined, as well as definitions of <TT>op<<</TT> + and <TT>op>></TT> that work with iostreams: <TT>op<<</TT> + prints <TT>(u,v)</TT> and <TT>op>></TT> can read <TT>u</TT>, + <TT>(u)</TT>, and <TT>(u,v)</TT>. + </P> + <P>Return <A HREF="#top">to top of page</A> or + <A HREF="../faq/index.html">to the FAQ</A>. + </P> + +<HR> +<H2><A NAME="2">Array Processing</A></H2> + <P>One of the major reasons why FORTRAN can chew through numbers so well + is that it is defined to be free of pointer aliasing, an assumption + that C89 is not allowed to make, and neither is C++. C99 adds a new + keyword, <TT>restrict</TT>, to apply to individual pointers. The C++ + solution is contained in the library rather than the language + (although many vendors can be expected to add this to their compilers + as an extension). + </P> + <P>That library solution is a set of two classes, five template classes, + and "a whole bunch" of functions. The classes are required + to be free of pointer aliasing, so compilers can optimize the + daylights out of them the same way that they have been for FORTRAN. + They are collectively called <TT>valarray</TT>, although strictly + speaking this is only one of the five template classes, and they are + designed to be familiar to people who have worked with the BLAS + libraries before. + </P> + <P>Some more stuff should go here once somebody has time to write it. + </P> + <P>Return <A HREF="#top">to top of page</A> or + <A HREF="../faq/index.html">to the FAQ</A>. + </P> + +<HR> +<H2><A NAME="3">Numerical Functions</A></H2> + <P>There are four generalized functions in the <numeric> header + that follow the same conventions as those in <algorithm>. Each + of them is overloaded: one signature for common default operations, + and a second for fully general operations. Their names are + self-explanatory to anyone who works with numerics on a regular basis: + <UL> + <LI><TT>accumulate</TT> + <LI><TT>inner_product</TT> + <LI><TT>partial_sum</TT> + <LI><TT>adjacent_difference</TT> + </UL> + </P> + <P>Here is a simple example of the two forms of <TT>accumulate</TT>. + <PRE> + int ar[50]; + int someval = somefunction(); + + // ...initialize members of ar to something... + + int sum = std::accumulate(ar,ar+50,0); + int sum_stuff = std::accumulate(ar,ar+50,someval); + int product = std::accumulate(ar,ar+50,1,std::multiplies<int>()); + </PRE> + The first call adds all the members of the array, using zero as an + initial value for <TT>sum</TT>. The second does the same, but uses + <TT>someval</TT> as the starting value (thus, <TT>sum_stuff == sum + + someval</TT>). The final call uses the second of the two signatures, + and multiplies all the members of the array; here we must obviously + use 1 as a starting value instead of 0. + </P> + <P>The other three functions have similar dual-signature forms. + </P> + <P>Return <A HREF="#top">to top of page</A> or + <A HREF="../faq/index.html">to the FAQ</A>. + </P> + + + +<!-- ####################################################### --> + +<HR> +<P CLASS="fineprint"><EM> +Comments and suggestions are welcome, and may be sent to +<A HREF="mailto:pme@sources.redhat.com">Phil Edwards</A> or +<A HREF="mailto:gdr@gcc.gnu.org">Gabriel Dos Reis</A>. +<BR> $Id: howto.html,v 1.7 2000/12/03 23:47:48 jsm28 Exp $ +</EM></P> + + +</BODY> +</HTML> |