Using and Porting GNU Fortran

• GNU GENERAL PUBLIC LICENSE
  • Preamble
  • TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
  • How to Apply These Terms to Your New Programs
• Contributors to GNU Fortran
• Funding Free Software
• Funding GNU Fortran
• Protect Your Freedom--Fight "Look And Feel"
• Getting Started
• What is GNU Fortran?
• Compile Fortran, C, or Other Programs
• GNU Fortran Command Options
  • Option Summary
  • Options Controlling the Kind of Output
  • Shorthand Options
  • Options Controlling Fortran Dialect
  • Options to Request or Suppress Warnings
  • Options for Debugging Your Program or GNU Fortran
  • Options That Control Optimization
  • Options Controlling the Preprocessor
  • Options for Directory Search
  • Options for Code Generation Conventions
  • Environment Variables Affecting GNU Fortran
• News About GNU Fortran
• User-visible Changes
• The GNU Fortran Language
  • Direction of Language Development
  • ANSI FORTRAN 77 Standard Support
    • No Passing External Assumed-length
    • No Passing Dummy Assumed-length
    • No Pathological Implied-DO
    • No Useless Implied-DO
  • Conformance
  • Notation Used in This Chapter
  • Fortran Terms and Concepts
    • Syntactic Items
    • Statements, Comments, and Lines
    • Scope of Symbolic Names and Statement Labels
  • Characters, Lines, and Execution Sequence
    • GNU Fortran Character Set
    • Lines
    • Continuation Line
    • Statements
    • Statement Labels
    • Order of Statements and Lines
    • Including Source Text
    • Cpp-style directives
  • Data Types and Constants
    • Data Types
      • Double Notation
      • Star Notation
      • Kind Notation
    • Constants
    • Integer Type
    • Character Type
  • Expressions
    • The %LOC() Construct
  • Specification Statements
    • NAMELIST Statement
    • DOUBLE COMPLEX Statement
  • Control Statements
    • DO WHILE
    • END DO
    • Construct Names
    • The CYCLE and EXIT Statements
  • Functions and Subroutines
    • The %VAL() Construct
    • The %REF() Construct
    • The %DESCR() Construct
    • Generics and Specifics
    • REAL() and AIMAG() of Complex
    • CMPLX() of DOUBLE PRECISION
    • MIL-STD 1753 Support
    • f77/f2c Intrinsics
    • Table of Intrinsic Functions
      • Abort Intrinsic
      • Abs Intrinsic
      • Access Intrinsic
      • AChar Intrinsic
      • ACos Intrinsic
      • AdjustL Intrinsic
      • AdjustR Intrinsic
      • AImag Intrinsic
      • AInt Intrinsic
      • Alarm Intrinsic
      • All Intrinsic
      • Allocated Intrinsic
      • ALog Intrinsic
      • ALog10 Intrinsic
      • AMax0 Intrinsic
      • AMax1 Intrinsic
      • AMin0 Intrinsic
      • AMin1 Intrinsic
      • AMod Intrinsic
      • And Intrinsic
      • ANInt Intrinsic
      • Any Intrinsic
      • ASin Intrinsic
      • Associated Intrinsic
      • ATan Intrinsic
      • ATan2 Intrinsic
      • BesJ0 Intrinsic
      • BesJ1 Intrinsic
      • BesJN Intrinsic
      • BesY0 Intrinsic
      • BesY1 Intrinsic
      • BesYN Intrinsic
      • Bit_Size Intrinsic
      • BTest Intrinsic
      • CAbs Intrinsic
      • CCos Intrinsic
      • Ceiling Intrinsic
      • CExp Intrinsic
      • Char Intrinsic
      • ChDir Intrinsic (subroutine)
      • ChMod Intrinsic (subroutine)
      • CLog Intrinsic
      • Cmplx Intrinsic
      • Complex Intrinsic
      • Conjg Intrinsic
      • Cos Intrinsic
      • CosH Intrinsic
      • Count Intrinsic
      • CPU_Time Intrinsic
      • CShift Intrinsic
      • CSin Intrinsic
      • CSqRt Intrinsic
      • CTime Intrinsic (subroutine)
      • CTime Intrinsic (function)
      • DAbs Intrinsic
      • DACos Intrinsic
      • DASin Intrinsic
      • DATan Intrinsic
      • DATan2 Intrinsic
      • Date_and_Time Intrinsic
      • DbesJ0 Intrinsic
      • DbesJ1 Intrinsic
      • DbesJN Intrinsic
      • DbesY0 Intrinsic
      • DbesY1 Intrinsic
      • DbesYN Intrinsic
      • Dble Intrinsic
      • DCos Intrinsic
      • DCosH Intrinsic
      • DDiM Intrinsic
      • DErF Intrinsic
      • DErFC Intrinsic
      • DExp Intrinsic
      • Digits Intrinsic
      • DiM Intrinsic
      • DInt Intrinsic
      • DLog Intrinsic
      • DLog10 Intrinsic
      • DMax1 Intrinsic
      • DMin1 Intrinsic
      • DMod Intrinsic
      • DNInt Intrinsic
      • Dot_Product Intrinsic
      • DProd Intrinsic
      • DSign Intrinsic
      • DSin Intrinsic
      • DSinH Intrinsic
      • DSqRt Intrinsic
      • DTan Intrinsic
      • DTanH Intrinsic
      • DTime Intrinsic (subroutine)
      • EOShift Intrinsic
      • Epsilon Intrinsic
      • ErF Intrinsic
      • ErFC Intrinsic
      • ETime Intrinsic (subroutine)
      • ETime Intrinsic (function)
      • Exit Intrinsic
      • Exp Intrinsic
      • Exponent Intrinsic
      • FDate Intrinsic (subroutine)
      • FDate Intrinsic (function)
      • FGet Intrinsic (subroutine)
      • FGetC Intrinsic (subroutine)
      • Float Intrinsic
      • Floor Intrinsic
      • Flush Intrinsic
      • FNum Intrinsic
      • FPut Intrinsic (subroutine)
      • FPutC Intrinsic (subroutine)
      • Fraction Intrinsic
      • FSeek Intrinsic
      • FStat Intrinsic (subroutine)
      • FStat Intrinsic (function)
      • FTell Intrinsic (subroutine)
      • FTell Intrinsic (function)
      • GError Intrinsic
      • GetArg Intrinsic
      • GetCWD Intrinsic (subroutine)
      • GetCWD Intrinsic (function)
      • GetEnv Intrinsic
      • GetGId Intrinsic
      • GetLog Intrinsic
      • GetPId Intrinsic
      • GetUId Intrinsic
      • GMTime Intrinsic
      • HostNm Intrinsic (subroutine)
      • HostNm Intrinsic (function)
      • Huge Intrinsic
      • IAbs Intrinsic
      • IAChar Intrinsic
      • IAnd Intrinsic
      • IArgC Intrinsic
      • IBClr Intrinsic
      • IBits Intrinsic
      • IBSet Intrinsic
      • IChar Intrinsic
      • IDate Intrinsic (UNIX)
      • IDiM Intrinsic
      • IDInt Intrinsic
      • IDNInt Intrinsic
      • IEOr Intrinsic
      • IErrNo Intrinsic
      • IFix Intrinsic
      • Imag Intrinsic
      • ImagPart Intrinsic
      • Index Intrinsic
      • Int Intrinsic
      • Int2 Intrinsic
      • Int8 Intrinsic
      • IOr Intrinsic
      • IRand Intrinsic
      • IsaTty Intrinsic
      • IShft Intrinsic
      • IShftC Intrinsic
      • ISign Intrinsic
      • ITime Intrinsic
      • Kill Intrinsic (subroutine)
      • Kind Intrinsic
      • LBound Intrinsic
      • Len Intrinsic
      • Len_Trim Intrinsic
      • LGe Intrinsic
      • LGt Intrinsic
      • Link Intrinsic (subroutine)
      • LLe Intrinsic
      • LLt Intrinsic
      • LnBlnk Intrinsic
      • Loc Intrinsic
      • Log Intrinsic
      • Log10 Intrinsic
      • Logical Intrinsic
      • Long Intrinsic
      • LShift Intrinsic
      • LStat Intrinsic (subroutine)
      • LStat Intrinsic (function)
      • LTime Intrinsic
      • MatMul Intrinsic
      • Max Intrinsic
      • Max0 Intrinsic
      • Max1 Intrinsic
      • MaxExponent Intrinsic
      • MaxLoc Intrinsic
      • MaxVal Intrinsic
      • MClock Intrinsic
      • MClock8 Intrinsic
      • Merge Intrinsic
      • Min Intrinsic
      • Min0 Intrinsic
      • Min1 Intrinsic
      • MinExponent Intrinsic
      • MinLoc Intrinsic
      • MinVal Intrinsic
      • Mod Intrinsic
      • Modulo Intrinsic
      • MvBits Intrinsic
      • Nearest Intrinsic
      • NInt Intrinsic
      • Not Intrinsic
      • Or Intrinsic
      • Pack Intrinsic
      • PError Intrinsic
      • Precision Intrinsic
      • Present Intrinsic
      • Product Intrinsic
      • Radix Intrinsic
      • Rand Intrinsic
      • Random_Number Intrinsic
      • Random_Seed Intrinsic
      • Range Intrinsic
      • Real Intrinsic
      • RealPart Intrinsic
      • Rename Intrinsic (subroutine)
      • Repeat Intrinsic
      • Reshape Intrinsic
      • RRSpacing Intrinsic
      • RShift Intrinsic
      • Scale Intrinsic
      • Scan Intrinsic
      • Second Intrinsic (function)
      • Second Intrinsic (subroutine)
      • Selected_Int_Kind Intrinsic
      • Selected_Real_Kind Intrinsic
      • Set_Exponent Intrinsic
      • Shape Intrinsic
      • Short Intrinsic
      • Sign Intrinsic
      • Signal Intrinsic (subroutine)
      • Sin Intrinsic
      • SinH Intrinsic
      • Sleep Intrinsic
      • Sngl Intrinsic
      • Spacing Intrinsic
      • Spread Intrinsic
      • SqRt Intrinsic
      • SRand Intrinsic
      • Stat Intrinsic (subroutine)
      • Stat Intrinsic (function)
      • Sum Intrinsic
      • SymLnk Intrinsic (subroutine)
      • System Intrinsic (subroutine)
      • System_Clock Intrinsic
      • Tan Intrinsic
      • TanH Intrinsic
      • Time Intrinsic (UNIX)
      • Time8 Intrinsic
      • Tiny Intrinsic
      • Transfer Intrinsic
      • Transpose Intrinsic
      • Trim Intrinsic
      • TtyNam Intrinsic (subroutine)
      • TtyNam Intrinsic (function)
      • UBound Intrinsic
      • UMask Intrinsic (subroutine)
      • Unlink Intrinsic (subroutine)
      • Unpack Intrinsic
      • Verify Intrinsic
      • XOr Intrinsic
      • ZAbs Intrinsic
      • ZCos Intrinsic
      • ZExp Intrinsic
      • ZLog Intrinsic
      • ZSin Intrinsic
      • ZSqRt Intrinsic
  • Scope and Classes of Symbolic Names
    • Underscores in Symbol Names
  • I/O
  • Fortran 90 Features
• Other Dialects
  • Source Form
    • Carriage Returns
    • Tabs
    • Short Lines
    • Long Lines
    • Ampersand Continuation Line
  • Trailing Comment
  • Debug Line
  • Dollar Signs in Symbol Names
  • Case Sensitivity
  • VXT Fortran
    • Meaning of Double Quote
    • Meaning of Exclamation Point in Column 6
  • Fortran 90
  • Pedantic Compilation
  • Distensions
    • Implicit Argument Conversion
    • Ugly Assumed-Size Arrays
    • Ugly Complex Part Extraction
    • Ugly Null Arguments
    • Ugly Conversion of Initializers
    • Ugly Integer Conversions
    • Ugly Assigned Labels
• The GNU Fortran Compiler
  • Compiler Limits
  • Run-time Environment Limits
    • Timer Wraparounds
    • Year 2000 (Y2K) Problems
    • Array Size
    • Character-variable Length
    • Year 10000 (Y10K) Problems
  • Compiler Types
  • Compiler Constants
  • Compiler Intrinsics
    • Intrinsic Groups
    • Other Intrinsics
      • ACosD Intrinsic
      • AIMax0 Intrinsic
      • AIMin0 Intrinsic
      • AJMax0 Intrinsic
      • AJMin0 Intrinsic
      • ASinD Intrinsic
      • ATan2D Intrinsic
      • ATanD Intrinsic
      • BITest Intrinsic
      • BJTest Intrinsic
      • CDAbs Intrinsic
      • CDCos Intrinsic
      • CDExp Intrinsic
      • CDLog Intrinsic
      • CDSin Intrinsic
      • CDSqRt Intrinsic
      • ChDir Intrinsic (function)
      • ChMod Intrinsic (function)
      • CosD Intrinsic
      • DACosD Intrinsic
      • DASinD Intrinsic
      • DATan2D Intrinsic
      • DATanD Intrinsic
      • Date Intrinsic
      • DbleQ Intrinsic
      • DCmplx Intrinsic
      • DConjg Intrinsic
      • DCosD Intrinsic
      • DFloat Intrinsic
      • DFlotI Intrinsic
      • DFlotJ Intrinsic
      • DImag Intrinsic
      • DReal Intrinsic
      • DSinD Intrinsic
      • DTanD Intrinsic
      • DTime Intrinsic (function)
      • FGet Intrinsic (function)
      • FGetC Intrinsic (function)
      • FloatI Intrinsic
      • FloatJ Intrinsic
      • FPut Intrinsic (function)
      • FPutC Intrinsic (function)
      • IDate Intrinsic (VXT)
      • IIAbs Intrinsic
      • IIAnd Intrinsic
      • IIBClr Intrinsic
      • IIBits Intrinsic
      • IIBSet Intrinsic
      • IIDiM Intrinsic
      • IIDInt Intrinsic
      • IIDNnt Intrinsic
      • IIEOr Intrinsic
      • IIFix Intrinsic
      • IInt Intrinsic
      • IIOr Intrinsic
      • IIQint Intrinsic
      • IIQNnt Intrinsic
      • IIShftC Intrinsic
      • IISign Intrinsic
      • IMax0 Intrinsic
      • IMax1 Intrinsic
      • IMin0 Intrinsic
      • IMin1 Intrinsic
      • IMod Intrinsic
      • INInt Intrinsic
      • INot Intrinsic
      • IZExt Intrinsic
      • JIAbs Intrinsic
      • JIAnd Intrinsic
      • JIBClr Intrinsic
      • JIBits Intrinsic
      • JIBSet Intrinsic
      • JIDiM Intrinsic
      • JIDInt Intrinsic
      • JIDNnt Intrinsic
      • JIEOr Intrinsic
      • JIFix Intrinsic
      • JInt Intrinsic
      • JIOr Intrinsic
      • JIQint Intrinsic
      • JIQNnt Intrinsic
      • JIShft Intrinsic
      • JIShftC Intrinsic
      • JISign Intrinsic
      • JMax0 Intrinsic
      • JMax1 Intrinsic
      • JMin0 Intrinsic
      • JMin1 Intrinsic
      • JMod Intrinsic
      • JNInt Intrinsic
      • JNot Intrinsic
      • JZExt Intrinsic
      • Kill Intrinsic (function)
      • Link Intrinsic (function)
      • QAbs Intrinsic
      • QACos Intrinsic
      • QACosD Intrinsic
      • QASin Intrinsic
      • QASinD Intrinsic
      • QATan Intrinsic
      • QATan2 Intrinsic
      • QATan2D Intrinsic
      • QATanD Intrinsic
      • QCos Intrinsic
      • QCosD Intrinsic
      • QCosH Intrinsic
      • QDiM Intrinsic
      • QExp Intrinsic
      • QExt Intrinsic
      • QExtD Intrinsic
      • QFloat Intrinsic
      • QInt Intrinsic
      • QLog Intrinsic
      • QLog10 Intrinsic
      • QMax1 Intrinsic
      • QMin1 Intrinsic
      • QMod Intrinsic
      • QNInt Intrinsic
      • QSin Intrinsic
      • QSinD Intrinsic
      • QSinH Intrinsic
      • QSqRt Intrinsic
      • QTan Intrinsic
      • QTanD Intrinsic
      • QTanH Intrinsic
      • Rename Intrinsic (function)
      • Secnds Intrinsic
      • Signal Intrinsic (function)
      • SinD Intrinsic
      • SnglQ Intrinsic
      • SymLnk Intrinsic (function)
      • System Intrinsic (function)
      • TanD Intrinsic
      • Time Intrinsic (VXT)
      • UMask Intrinsic (function)
      • Unlink Intrinsic (function)
      • ZExt Intrinsic
• Other Compilers
  • Dropping f2c Compatibility
  • Compilers Other Than f2c
• Other Languages
  • Tools and advice for interoperating with C and C++
    • C Interfacing Tools
    • Accessing Type Information in C
    • Generating Skeletons and Prototypes with f2c
    • C++ Considerations
    • Startup Code
• Installing GNU Fortran
  • Prerequisites
  • Problems Installing
    • General Problems
      • GNU C Required
      • Patching GNU CC
      • Building GNU CC Necessary
      • Missing strtoul or bsearch
      • Cleanup Kills Stage Directories
      • LANGUAGES Macro Ignored
    • System-specific Problems
    • Cross-compiler Problems
  • Changing Settings Before Building
    • Larger File Unit Numbers
    • Always Flush Output
    • Maximum Stackable Size
    • Floating-point Bit Patterns
    • Initialization of Large Aggregate Areas
    • Alpha Problems Fixed
  • Quick Start
  • Complete Installation
  • Distributing Binaries
• Debugging and Interfacing
  • Main Program Unit (PROGRAM)
  • Procedures (SUBROUTINE and FUNCTION)
  • Functions (FUNCTION and RETURN)
  • Names
  • Common Blocks (COMMON)
  • Local Equivalence Areas (EQUIVALENCE)
  • Complex Variables (COMPLEX)
  • Arrays (DIMENSION)
  • Adjustable Arrays (DIMENSION)
  • Alternate Entry Points (ENTRY)
  • Alternate Returns (SUBROUTINE and RETURN)
  • Assigned Statement Labels (ASSIGN and GOTO)
  • Run-time Library Errors
• Collected Fortran Wisdom
  • Advantages Over f2c
    • Language Extensions
    • Diagnostic Abilities
    • Compiler Options
    • Compiler Speed
    • Program Speed
    • Ease of Debugging
    • Character and Hollerith Constants
  • Block Data and Libraries
  • Loops
  • Working Programs
    • Not My Type
    • Variables Assumed To Be Zero
    • Variables Assumed To Be Saved
    • Unwanted Variables
    • Unused Arguments
    • Surprising Interpretations of Code
    • Aliasing Assumed To Work
    • Output Assumed To Flush
    • Large File Unit Numbers
    • Floating-point precision
    • Inconsistent Calling Sequences
  • Overly Convenient Command-line Options
  • Faster Programs
    • Aligned Data
    • Prefer Automatic Uninitialized Variables
    • Avoid f2c Compatibility
    • Use Submodel Options
• Known Causes of Trouble with GNU Fortran
  • Bugs Not In GNU Fortran
    • Signal 11 and Friends
    • Cannot Link Fortran Programs
    • Large Common Blocks
    • Debugger Problems
    • NeXTStep Problems
    • Stack Overflow
    • Nothing Happens
    • Strange Behavior at Run Time
    • Floating-point Errors
  • Known Bugs In GNU Fortran
  • Missing Features
    • Better Source Model
    • Fortran 90 Support
    • Intrinsics in PARAMETER Statements
    • Arbitrary Concatenation
    • SELECT CASE on CHARACTER Type
    • RECURSIVE Keyword
    • Increasing Precision/Range
    • Popular Non-standard Types
    • Full Support for Compiler Types
    • Array Bounds Expressions
    • POINTER Statements
    • Sensible Non-standard Constructs
    • READONLY Keyword
    • FLUSH Statement
    • Expressions in FORMAT Statements
    • Explicit Assembler Code
    • Q Edit Descriptor
    • Old-style PARAMETER Statements
    • TYPE and ACCEPT I/O Statements
    • STRUCTURE, UNION, RECORD, MAP
    • OPEN, CLOSE, and INQUIRE Keywords
    • ENCODE and DECODE
    • AUTOMATIC Statement
    • Suppressing Space Padding of Source Lines
    • Fortran Preprocessor
    • Bit Operations on Floating-point Data
    • Really Ugly Character Assignments
    • POSIX Standard
    • Floating-point Exception Handling
    • Nonportable Conversions
    • Large Automatic Arrays
    • Support for Threads
    • Enabling Debug Lines
    • Better Warnings
    • Gracefully Handle Sensible Bad Code
    • Non-standard Conversions
    • Non-standard Intrinsics
    • Modifying DO Variable
    • Better Pedantic Compilation
    • Warn About Implicit Conversions
    • Invalid Use of Hollerith Constant
    • Dummy Array Without Dimensioning Dummy
    • Invalid FORMAT Specifiers
    • Ambiguous Dialects
    • Unused Labels
    • Informational Messages
    • Uninitialized Variables at Run Time
    • Portable Unformatted Files
    • Better List-directed I/O
    • Default to Console I/O
    • Labels Visible to Debugger
  • Disappointments and Misunderstandings
    • Mangling of Names in Source Code
    • Multiple Definitions of External Names
    • Limitation on Implicit Declarations
  • Certain Changes We Don't Want to Make
    • Backslash in Constants
    • Initializing Before Specifying
    • Context-Sensitive Intrinsicness
    • Context-Sensitive Constants
    • Equivalence Versus Equality
    • Order of Side Effects
  • Warning Messages and Error Messages
• Open Questions
• Reporting Bugs
  • Have You Found a Bug?
  • Where to Report Bugs
  • How to Report Bugs
  • Sending Patches for GNU Fortran
• How To Get Help with GNU Fortran
• Adding Options
• Projects
  • Improve Efficiency
  • Better Optimization
  • Simplify Porting
  • More Extensions
  • Machine Model
  • Internals Documentation
  • Internals Improvements
  • Better Diagnostics
• Front End
  • Overview of Sources
  • Overview of Translation Process
    • g77stripcard
    • lex.c
    • sta.c
    • stb.c
    • expr.c
    • stc.c
    • std.c
    • ste.c
    • Gotchas (Transforming)
      • Multi-character Lexemes
      • Space-padding Lexemes
      • Bizarre Free-form Hollerith Constants
      • Hollerith Constants
      • Confusing Function Keyword
      • Weird READ
    • TBD (Transforming)
  • Philosophy of Code Generation
  • Two-pass Design
    • Two-pass Code
    • Why Two Passes
  • Challenges Posed
  • Transforming Statements
    • Statements Needing Temporaries
    • Transforming DO WHILE
    • Transforming Iterative DO
    • Transforming Block IF
    • Transforming SELECT CASE
  • Transforming Expressions
  • Internal Naming Conventions
• Diagnostics
  • CMPAMBIG
  • EXPIMP
  • INTGLOB
  • LEX
  • GLOBALS
  • LINKFAIL
  • Y2KBAD
• Index