Requirements for Fortran 2003

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• Requirements for Fortran 2003
• Procedures and Progress
• David Muxworthy
• BSI Fortran Convenor
• Prepared for the BCS FSG meeting on 10 March 2005
• Almost all the content is based on material
  accessible via links from the factsheet

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Fortran StandardsRevision Cycle
1962 First ANSI standardization committee
meets 1966 Publication of ANSI standard (ISO
1972) 1978 Fortran 77 (ISO 1980) relatively
minor revision 1991 Fortran 90 - major
revision 1997 Fortran 95 - minor
revision 2004 Fortran 2003 - major revision
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F2003 Revision Schedule
Repository started 2004-05 Preliminary choice
of significant features 2005-04Final choice of
significant features 2006-02 Completion of
separate edits 2006-05First working draft
available 2007-05 First CD submitted for
registration and approval 2007-10 Final CD
submitted for approval 2008-09 WG5 approval of
draft DIS 2009-04DIS ballot initiated 2009-0
5DIS ballot results available 2009-07Standard
published 2009-08
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Requirements collection procedure

• ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
  ? ? ?
• National member National member National
  member ....
• of ISO of ISO of ISO
• WG5 repository
• of requirements
• WG5 decide at May 2005
• and February 2006 meetings
• Final set of requirements
• for Fortran 2003

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Repository item headings
Number Title Submitted By Status Severity
Level References Basic FunctionalityRationaleEst
imated ImpactDiscussionDetailed
SpecificationHistory
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Severity Levels - Editorial
1. Minor editorial (less than 10 lines
altered).2. Significant editorial (up to a page
altered) with no technical change.3. Major
editorial (up to a chapter altered) with no
technical change.
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Severity Levels Technical (1)

• 3. Very minor technical change.
• An example is adding the optional argument KIND
  to IACHAR.
• Minor technical change.
• An example is changing type-bound generics to be
  sets of specific named type-bound procedures.
• 5. Technical change likely to need more than two
  J3 meetings to develop.An example is
  reallocation of allocatable arrays.

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Severity Levels Technical (2)
6. Technical change likely to need more than a
year to develop. The modules and allocatable
TRs are examples.7. Technical change likely to
need more than 2 years to develop. The IEEE TR
is an example.8. Technical change likely to
need more than 3 years to develop. Interfacing
with C and the OO features are examples.
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WG5 RepositorySubmissions so far

• level 3 18
• level 3/4 1
• level 4 13
• level 5 1
• level 6 2
• total 31

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WG5 RepositoryUK submissions

• UK-001 6 Co-array Fortran for parallel
  programming
• UK-002 3 Decimal floating point arithmetic
• UK-003 4 Conformance to IEEE 754R
• UK-004 3 KIND environment specification

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UK-001 Co-array Fortranfor parallel programming

• Co-Array Fortran is a simple parallel extension
• ? assumes the SPMD programming model with the
  program,
• both text and data, replicated a fixed
  number of times
• ? each copy is called an image
• ? normal subscripts refer to memory addresses
  within an
• image while a second set of subscripts refer
  to memory
• addresses in other images
• ? each image executes asynchronously with
  explicit
• synchronization provided by the programmer.

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UK-002 Decimal floating point arithmetic

• Allow for decimal floating point
  arithmeticLanguages increasingly support
  decimal arithmetic in addition to binary or
  hexadecimal arithmetic, e.g. C, COBOL, Visual
  Basic. Now that IBM are to sell hardware with
  packed decimal floating point, the C and C WGs
  are preparing TRs to extend those languages to
  provide decimal floating-point facilities,
  principally for financial applications. In order
  to retain competitiveness and to maintain
  interoperability with C, Fortran should adopt
  comparable facilities.

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UK-003 Conformance to IEEE 754R

• Allow for decimal floating point arithmetic in
  conformance withIEEE 754R
• Other languages, notably C and C, are being
  extended to accommodate features of IEEE 754R,
  principally for decimal floating point
  arithmetic. In order to retain interoperability
  with C, Fortran should adopt comparable
  facilities.
• The 754R standard is still being developed.

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UK-004 KIND environment specification

• Provide parameter arrays in ISO_FORTRAN_ENV that
  define the number and available kind values for
  each intrinsic type.Declarations like the
  following should be defined in ISO_FORTRAN_ENV
• INTEGER,PARAMETER FP_KINDS(3) 4,8,16,
  INT_KINDS(2) 4,2, CHAR_KINDS(1)
  1...
• ? FP_KINDS(1) must be the value for KIND(0.0E0)
  and
• FP_KINDS(2) that forKIND(0.0D0)
• ? The first element in each array must contain
  the kind value for the
• default intrinsic type
• ? An inquiry as to the SIZE(FP_KINDS) will return
  the number of
• floating point, etc. representation methods
  available

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J3 Submissions - Editorial

• Rewrite attribute requirements (J3-008, level 3)
• The current method of specifying the requirements
  on various attributes, such as EXTERNAL and
  POINTER, is too hard to understand and too prone
  to error. The attribute specification parts of
  chapters 5 and 12 should be rewritten.

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J3 Submissions - Types Data Objects

• Allow TYPE ( ltintrinsic-type-specgt ) (j3-020,
  level 3)
• For regularity and symmetry, allow TYPE (
  ltintrinsic-type-specgt )
• Allow forward type for allocatable components
  (j3-028, level 3)
• Do not require the type of an allocatable
  component to be defined before the type
  containing the allocatable component.
• Named rank-one array constant's extent from its
  ltinitialization-exprgt (j3-023, level 3)
• As with the length of a character named constant,
  allow a rank-one array named constant to get its
  extent from the ltinitialization-exprgt.

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J3 Submissions - Expressions

• ANDTHEN and ORELSE pseudo-functions (j3-031,
  level 4)
• Guarantee short-circuit evaluation of AND and OR
  operations. Add two new elemental
  pseudo-functions
• ANDTHEN (A1 ,A2 , A3, ...AN )
• ORELSE (A1 ,A2 , A3, ...AN )
• Arguments
• A1, ...AN Logical, of any kind, they
  must be conformable
• The arguments are evaluated in sequence, left
  to right, one at a time.

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J3 Submissions - Assignment

• Allow a polymorphic allocatable variable in
  intrinsic assignment (j3-022, level 4)
• Require ltexprgt to have the same rank as a
  polymorphic ltvariablegt. If ltvariablegt is
  allocated and polymorphic, deallocate it. Then
  allocate it with the same dynamic type, type
  parameters and bounds as ltexprgt.
• Updating complex parts (j3-015, level 4)
• Specify that the real and imaginary parts of a
  complex variable can be accessed by using
  component-like syntax, with "component" names
  REAL and AIMAG.

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J3 Submissions - Execution control

• Enhance the STOP statement (j3-001, level 3)
• Stop code should allow a scalar integer or
  character expression, be displayed on ERROR_UNIT,
  if the stop code is integer, it should be used as
  the process exit status
• EXIT from any labelled construct (j3-024, level
  3)
• Allow EXIT from any labelled construct (not just
  loops)

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J3 Submissions - Procedures (1)

• Allow empty CONTAINS part (j3-010, level 3)
• To facilitate program development and use of
  automatically generated programs
• Internal subprograms as actual arguments and
  procedure pointer targets (j3-013, level 4)
• Allow internal subprograms as actual arguments
  and procedure pointer targets

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J3 Submissions - Procedures (2)

• Disassociated or deallocated actual argument
  associated with nonpointer nonallocatable
  optional dummy argument is considered not to be
  present (j3-016, level 4)
• The title says it all
• (At the February 2005 J3 meeting this item was
  allocated lowest priority so far as J3 is
  concerned)
• Default initial values for absent optional dummy
  arguments
• (j3-017,level 4)
• Allow specificiation of a default initial value
  for absent optional dummy arguments.

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J3 Submissions - Procedures (3)

• Non-null initial targets for pointers (j3-018,
  level 4)
• Allow initial targets for pointers that are other
  than NULL()
• (At the February 2005 J3 meeting this item was
  allocated lowest priority so far as J3 is
  concerned)
• Allow SUBROUTINE ltnamegt or FUNCTION ltnamegt to be
  optional on END statements for module and
  internal subprograms
• (j3-025, level 3)
• Module procedures are required to end with END
  SUBROUTINE ltnamegt or END FUNCTION ltnamegt. This
  is generally a good thing, but it makes it
  impossible to convert a Fortran 77 external
  procedure to a module procedure by using INCLUDE

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J3 Submissions - Intrinsic Procedures(1)

• More mathematical functions (j3-019, level 4)
• Provide ACOS, ASIN, ATAN, COSH, SINH, TAN and
  TANH for complex type. Provide inverse
  hyperbolic functions, including for complex type.
  In the case of TAN, specify that the real part
  of the argument is regarded as a value in
  radians.
• Make ATAN with two arguments work like ATAN2
  (j3-026, level 3)
• Since ATAN is generic, it is surprising to
  students that they need to use ATAN2 just because
  they have the two-argument formulation.

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J3 Submissions - Intrinsic Procedures (2)

• ASCII arguments for LGE etc (j3-027, level 3)
• Allow ASCII kind characters as arguments to LGE,
  LGT, LLE and LLT
• More info on GET_COMMAND_ARGUMENT failure
  (j3-029, level 3)
• Provide more information if GET_COMMAND or
  GET_COMMAND_ARGUMENT fails.

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J3 Submissions - ISO_FORTRAN_ENV (1)

• GET_IO_UNIT (j3-002, level 3)
• Add an procedure to ISO_FORTRAN_ENV to return a
  logical unit number which may be opened.
• IO_UNIT standard derived type (j3-009, level 4)
• Add a derived type to ISO_FORTRAN_ENV to
  represent an i/o unit. Allow values of this type
  to be used everywhere that a unit number can be
  used.

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J3 Submissions - ISO_FORTRAN_ENV (2)

• EXECUTE_COMMAND_LINE (j3-003, level 4)
• Add a procedure to ISO_FORTRAN_ENV to cause an
  external program to execute.
• (At the February 2005 J3 meeting this item was
  allocated lowest priority so far as J3 is
  concerned)
• STORAGE_SIZE (j3-004, level 3)
• Add a procedure to ISO_FORTRAN_ENV to return the
  size in bits of its argument.

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J3 Submissions - ISO_FORTRAN_ENV (3)

• Find logical and character kinds (j3-006, level
  3)
• Add constants to iso_fortran_env which specify
  all available logical kind values and all
  available character kind names (Overlaps UK-004).
• Selection of most common real and integer kinds
  (j3-030, level 3)
• The standard should specify named constants in
  the ISO_FORTRAN_ENV intrinsic module, as an
  example int8_kind, int16_kind, int32_kind,
  int64_kind, real32_kind, real64_kind,
  real128_kind, int_default_kind,
  real_default_kind, real_double_kind
• (At the February 2005 J3 meeting this item was
  allocated lowest priority so far as J3 is
  concerned)

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J3 Submissions - ISO_C_BINDING

• C_SIZEOF (j3-005, level 3)
• Add a procedure to ISO_C_BINDING to return the
  size of its argument as per C sizeof.

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J3 Submissions - Scope association

• Construct Name Local to Construct (j3-007, level
  3/4)
• Make a construct name be local to its construct.
• Use ALLOCATABLE and POINTER attributes in generic
  resolution (j3-012, level 4)
• Allow the POINTER and ALLOCATABLE attributes to
  be used as the last resort for generic
  resolution.
• Resolve generic without invoking a procedure or
  evaluating arguments (j3-021, level 4)
• Given exemplars of actual arguments, resolve a
  generic name to a specific procedure without
  invoking the procedure or evaluating its
  arguments.
• (At the February 2005 J3 meeting this item was
  allocated lowest priority so far as J3 is
  concerned)

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J3 Submissions - Coroutines

• Coroutines (J3-011, level 5)
• Provide coroutines to facilitate library
  procedures accessing user-supplied code. Add two
  new statements, called for example SUSPEND and
  RESUME. Provide a new form of subprogram, the
  "coroutine", that cannot contain an ENTRY
  statement, and is the only subprogram in which a
  SUSPEND statement is allowed. A coroutine
  requires an explicit interface.
• (At the February 2005 J3 meeting this item was
  allocated lowest priority so far as J3 is
  concerned)

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J3 Submissions - Parameterized modules

• Parameterized modules (J3-014, level 6)
• Provide a facility whereby a module or subprogram
  can be developed in a generic form, and then
  applied to any appropriate type.

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J3' s classification - "must do" itemsgreen gt
already in the WG5 repository

• Description Level
• Co-array Fortran for parallel programming 6
• Parameterized Modules 6
• Pointers to contiguous memory 5
• Same Assumed Shape declaration 5
• DO CONCURRENT construct 5
• Math Intrinsics complex trig 4
• Rewrite attribute requirements 3
• Type ( Intrinsic-type) 3
• Ascii in LGE etc 3

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J3' s classification - "do if time" items (1)

• Description Level
• TYPELESS object 7
• Avoid obtaining a logical unit for opening 5
• Allocatable/Pointer in Generic Resolve 5
• Conformance to IEEE 754R 4
• STORAGE_SIZE intrinsic 4
• Construct names Local to Construct 4
• Internal Procedures as actual args 4
• Updating Complex parts 4
• Default for Optional Dummy 4
• Polymorphic allocatable ltvariablegt in intrinsic
  assignment 4
• .ANDTHEN. .ORELSE. 4
• Pointers and Targets specify all possible
  pointers for a target and vv 4
• Library extensions Bessel, erf, gamma, hypot 4
• Rank gt 7 4
• Compute if actual arg is present 4
• Interoperability of pointers, allocatables, and
  assumed-shape arrays 4
• Interoperability of optional arguments 4

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J3' s classification - "do if time" items (2)

• Description Level
• Decimal floating-point arithmetic 3
• Stop - exit code 3
• Get logical I/O unit number 3
• C_sizeof 3
• Finding Logical Character Kinds 3
• Allow empty CONTAINS part 3
• Size/shape of Parameter Array 3
• Exit from any labelled Construct 3
• Name Optional on END module internal
  subprogram 3
• Atan/Atan2 3
• Public 116 Forward Allocatable 3
• More information about GET_COMMAND_ARGUMENT
  failure 3
• Findloc find location of element in an array
  having specified value 3
• Mold on Allocate 3
• Proposed f2k MTE on semicolons allow at start
  of line 3

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J3' s classification - "low priority" items

• Description Level
• Coroutines 5
• Behavior of -0.0 in intrinsics (subsumed by
  interp F03/0049) 5
• Execute External program intrinsic 4
• Disassoc/dealloc actual gt not Present 4
• Non-null Initial Targets 4
• Resolve generic without invoking a procedure or
  evaluating arguments 4
• "Use, Not " 4
• Simplified Kind Selection 3
• Compiler Version char constant in
  ISO_FORTRAN_ENV 3

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Recent submission for consideration from UK (1)

• Allow references to functions returning an
  associated pointer to appear as actual arguments
  associated with INTENT(OUT) dummies. This is
  parallel to the way we treat regular
  pointers.ExampleFUNCTION storage(key)
  RESULT(loc) INTEGER, INTENT(IN) key
  REAL, POINTER loc locgt...END FUNCTION
  ! Make the following legalCALL
  RANDOM_NUMBER(storage(10))

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Recent submission for consideration from UK (2)

• Allow references to functions returning an
  associated pointer to appear as the lhs of
  assignment statement, where the value of the
  target is changed. This is parallel to the way we
  treat regular pointers.ExampleFUNCTION
  storage(key) RESULT(loc) INTEGER, INTENT(IN)
  key REAL, POINTER loc locgt...END
  FUNCTION ! Make the following
  legalstorage(5)0.5