X-Git-Url: https://oss.titaniummirror.com/gitweb/?a=blobdiff_plain;f=libstdc%2B%2B-v3%2Fdocs%2Fhtml%2F26_numerics%2Fhowto.html;fp=libstdc%2B%2B-v3%2Fdocs%2Fhtml%2F26_numerics%2Fhowto.html;h=0000000000000000000000000000000000000000;hb=6fed43773c9b0ce596dca5686f37ac3fc0fa11c0;hp=ef0b36a8eacb48379b9953166d44b05f403ba0a4;hpb=27b11d56b743098deb193d510b337ba22dc52e5c;p=msp430-gcc.git diff --git a/libstdc++-v3/docs/html/26_numerics/howto.html b/libstdc++-v3/docs/html/26_numerics/howto.html deleted file mode 100644 index ef0b36a8..00000000 --- a/libstdc++-v3/docs/html/26_numerics/howto.html +++ /dev/null @@ -1,171 +0,0 @@ - - - - - - - - - - - libstdc++-v3 HOWTO: Chapter 26 - - - - -

Chapter 26: Numerics

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Chapter 26 deals with building block abstractions to aid in - numerical computing: -

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All of the Standard C math functions are of course included in C++, - and overloaded versions for long, float, and - long double have been added for all of them. -

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Contents

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Complex Number Processing

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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. -

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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). -

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Return to top of page or - to the FAQ. -

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Array Processing

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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). -

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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. -

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Some more stuff should go here once somebody has time to write it. -

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Return to top of page or - to the FAQ. -

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Numerical Functions

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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: -

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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>());
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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. -

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The other three functions have similar dual-signature forms. -

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Return to top of page or - to the FAQ. -

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C99

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In addition to the other topics on this page, we'll note here some - of the C99 features that appear in libstdc++-v3. -

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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. -

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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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Return to top of page or - to the FAQ. -

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-See license.html for copying conditions. -Comments and suggestions are welcome, and may be sent to -the libstdc++ mailing list. -

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