From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- libstdc++-v3/doc/xml/manual/numerics.xml | 145 +++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 libstdc++-v3/doc/xml/manual/numerics.xml (limited to 'libstdc++-v3/doc/xml/manual/numerics.xml') diff --git a/libstdc++-v3/doc/xml/manual/numerics.xml b/libstdc++-v3/doc/xml/manual/numerics.xml new file mode 100644 index 000000000..a9e866e78 --- /dev/null +++ b/libstdc++-v3/doc/xml/manual/numerics.xml @@ -0,0 +1,145 @@ + + + + + Numerics + <indexterm><primary>Numerics</primary></indexterm> + + + + ISO C++ + + + library + + + + + + + +
Complex + + + + +
complex Processing + + + + Using complex<> becomes even more comple- er, sorry, + complicated, 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 +here. + + complex<> 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 op<< + and op>> that work with iostreams: op<< + prints (u,v) and op>> can read u, + (u), and (u,v). + + +
+
+ + +
Generalized Operations + + + + + + 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: + + + accumulate + inner_product + chapterial_sum + adjacent_difference + + Here is a simple example of the two forms of accumulate. + + + 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>()); + + The first call adds all the members of the array, using zero as an + initial value for sum. The second does the same, but uses + someval as the starting value (thus, sum_stuff == sum + + someval). 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. + + The other three functions have similar dual-signature forms. + + +
+ + +
Interacting with C + + + +
Numerics vs. Arrays + + + 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++98. C99 adds a new + keyword, restrict, 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). + + 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 valarray, 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. + + +
+ +
C99 + + + In addition to the other topics on this page, we'll note here some + of the C99 features that appear in libstdc++. + + The C99 features depend on the --enable-c99 configure flag. + This flag is already on by default, but it can be disabled by the + user. Also, the configuration machinery will disable it if the + necessary support for C99 (e.g., header files) cannot be found. + + As of GCC 3.0, C99 support includes classification functions + such as isnormal, isgreater, + isnan, etc. + The functions used for 'long long' support such as strtoll + are supported, as is the lldiv_t typedef. Also supported + are the wide character functions using 'long long', like + wcstoll. + + +
+
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