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diff --git a/share/doc/gfortran/About-GNU-Fortran.html b/share/doc/gfortran/About-GNU-Fortran.html new file mode 100644 index 0000000..e9005f7 --- /dev/null +++ b/share/doc/gfortran/About-GNU-Fortran.html @@ -0,0 +1,197 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1999-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>The GNU Fortran Compiler: About GNU Fortran</title> + +<meta name="description" content="The GNU Fortran Compiler: About GNU Fortran"> +<meta name="keywords" content="The GNU Fortran Compiler: About GNU Fortran"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Introduction.html#Introduction" rel="up" title="Introduction"> +<link href="GNU-Fortran-and-GCC.html#GNU-Fortran-and-GCC" rel="next" title="GNU Fortran and GCC"> +<link href="Introduction.html#Introduction" rel="previous" title="Introduction"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="About-GNU-Fortran"></a> +<div class="header"> +<p> +Next: <a href="GNU-Fortran-and-GCC.html#GNU-Fortran-and-GCC" accesskey="n" rel="next">GNU Fortran and GCC</a>, Up: <a href="Introduction.html#Introduction" accesskey="u" rel="up">Introduction</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="About-GNU-Fortran-1"></a> +<h3 class="section">1.1 About GNU Fortran</h3> + +<p>The GNU Fortran compiler is the successor to <code>g77</code>, the +Fortran 77 front end included in GCC prior to version 4 (released in +2005). While it is backward-compatible with most <code>g77</code> +extensions and command-line options, <code>gfortran</code> is a completely new +implemention designed to support more modern dialects of Fortran. +GNU Fortran implements the Fortran 77, 90 and 95 standards +completely, most of the Fortran 2003 and 2008 standards, and some +features from the 2018 standard. It also implements several extensions +including OpenMP and OpenACC support for parallel programming. +</p> +<p>The GNU Fortran compiler passes the +<a href="http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html">NIST Fortran 77 Test Suite</a>, and produces acceptable results on the +<a href="https://www.netlib.org/lapack/faq.html">LAPACK Test Suite</a>. +It also provides respectable performance on +the <a href="https://polyhedron.com/?page_id=175">Polyhedron Fortran compiler benchmarks</a> and the +<a href="https://www.netlib.org/benchmark/livermore">Livermore Fortran Kernels test</a>. It has been used to compile a number of +large real-world programs, including +<a href="http://hirlam.org/">the HARMONIE and HIRLAM weather forecasting code</a> and +<a href="https://github.com/dylan-jayatilaka/tonto">the Tonto quantum chemistry package</a>; see +<a href="https://gcc.gnu.org/wiki/GfortranApps">https://gcc.gnu.org/wiki/GfortranApps</a> for an extended list. +</p> +<p>GNU Fortran provides the following functionality: +</p> +<ul> +<li> Read a program, stored in a file and containing <em>source code</em> +instructions written in Fortran 77. + +</li><li> Translate the program into instructions a computer +can carry out more quickly than it takes to translate the +original Fortran instructions. +The result after compilation of a program is +<em>machine code</em>, +which is efficiently translated and processed +by a machine such as your computer. +Humans usually are not as good writing machine code +as they are at writing Fortran (or C++, Ada, or Java), +because it is easy to make tiny mistakes writing machine code. + +</li><li> Provide information about the reasons why +the compiler may be unable to create a binary from the source code, +for example if the source code is flawed. +The Fortran language standards require that the compiler can point out +mistakes in your code. +An incorrect usage of the language causes an <em>error message</em>. + +<p>The compiler also attempts to diagnose cases where your +program contains a correct usage of the language, +but instructs the computer to do something questionable. +This kind of diagnostic message is called a <em>warning message</em>. +</p> +</li><li> Provide optional information about the translation passes +from the source code to machine code. +This can help you to find the cause of +certain bugs which may not be obvious in the source code, +but may be more easily found at a lower level compiler output. +It also helps developers to find bugs in the compiler itself. + +</li><li> Provide information in the generated machine code that can +make it easier to find bugs in the program (using a debugging tool, +called a <em>debugger</em>, such as the GNU Debugger <code>gdb</code>). + +</li><li> Locate and gather machine code already generated to +perform actions requested by statements in the program. +This machine code is organized into <em>modules</em> and is located +and <em>linked</em> to the user program. +</li></ul> + +<p>The GNU Fortran compiler consists of several components: +</p> +<ul> +<li> A version of the <code>gcc</code> command +(which also might be installed as the system’s <code>cc</code> command) +that also understands and accepts Fortran source code. +The <code>gcc</code> command is the <em>driver</em> program for +all the languages in the GNU Compiler Collection (GCC); +With <code>gcc</code>, +you can compile the source code of any language for +which a front end is available in GCC. + +</li><li> The <code>gfortran</code> command itself, +which also might be installed as the +system’s <code>f95</code> command. +<code>gfortran</code> is just another driver program, +but specifically for the Fortran compiler only. +The primary difference between the <code>gcc</code> and <code>gfortran</code> +commands is that the latter automatically links the correct libraries +to your program. + +</li><li> A collection of run-time libraries. +These libraries contain the machine code needed to support +capabilities of the Fortran language that are not directly +provided by the machine code generated by the +<code>gfortran</code> compilation phase, +such as intrinsic functions and subroutines, +and routines for interaction with files and the operating system. + +</li><li> The Fortran compiler itself, (<code>f951</code>). +This is the GNU Fortran parser and code generator, +linked to and interfaced with the GCC backend library. +<code>f951</code> “translates” the source code to +assembler code. You would typically not use this +program directly; +instead, the <code>gcc</code> or <code>gfortran</code> driver +programs call it for you. +</li></ul> + + + +<hr> +<div class="header"> +<p> +Next: <a href="GNU-Fortran-and-GCC.html#GNU-Fortran-and-GCC" accesskey="n" rel="next">GNU Fortran and GCC</a>, Up: <a href="Introduction.html#Introduction" accesskey="u" rel="up">Introduction</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |