A categorization of standard (2018) and extended Fortran intrinsic procedures¶
This note attempts to group the intrinsic procedures of Fortran into categories of functions or subroutines with similar interfaces as an aid to comprehension beyond that which might be gained from the standard’s alphabetical list.
A brief status of intrinsic procedure support in f18 is also given at the end.
Few procedures are actually described here apart from their interfaces; see the Fortran 2018 standard (section 16) for the complete story.
Intrinsic modules are not covered here.
General rules¶
The value of any intrinsic function’s
KIND
actual argument, if present, must be a scalar constant integer expression, of any kind, whose value resolves to some supported kind of the function’s result type. If optional and absent, the kind of the function’s result is either the default kind of that category or to the kind of an argument (e.g., as inAINT
).Procedures are summarized with a nonFortran syntax for brevity. Wherever a function has a short definition, it appears after an equal sign as if it were a statement function. Any functions referenced in these short summaries are intrinsic.
Unless stated otherwise, an actual argument may have any supported kind of a particular intrinsic type. Sometimes a pattern variable can appear in a description (e.g.,
REAL(k)
) when the kind of an actual argument’s type must match the kind of another argument, or determines the kind type parameter of the function result.When an intrinsic type name appears without a kind (e.g.,
REAL
), it refers to the default kind of that type. Sometimes the worddefault
will appear for clarity.The names of the dummy arguments actually matter because they can be used as keywords for actual arguments.
All standard intrinsic functions are pure, even when not elemental.
Assumedrank arguments may not appear as actual arguments unless expressly permitted.
When an argument is described with a default value, e.g.
KIND=KIND(0)
, it is an optional argument. Optional arguments without defaults, e.g.DIM
on many transformationals, are wrapped in[]
brackets as in the Fortran standard. When an intrinsic has optional arguments with and without default values, the arguments with default values may appear within the brackets to preserve the order of arguments (e.g.,COUNT
).
Elemental intrinsic functions¶
Pure elemental semantics apply to these functions, to wit: when one or more of the actual arguments are arrays, the arguments must be conformable, and the result is also an array. Scalar arguments are expanded when the arguments are not all scalars.
Elemental intrinsic functions that may have unrestricted specific procedures¶
When an elemental intrinsic function is documented here as having an
unrestricted specific name, that name may be passed as an actual
argument, used as the target of a procedure pointer, appear in
a generic interface, and be otherwise used as if it were an external
procedure.
An INTRINSIC
statement or attribute may have to be applied to an
unrestricted specific name to enable such usage.
When a name is being used as a specific procedure for any purpose other
than that of a called function, the specific instance of the function
that accepts and returns values of the default kinds of the intrinsic
types is used.
A Fortran INTERFACE
could be written to define each of
these unrestricted specific intrinsic function names.
Calls to dummy arguments and procedure pointers that correspond to these specific names must pass only scalar actual argument values.
No other intrinsic function name can be passed as an actual argument,
used as a pointer target, appear in a generic interface, or be otherwise
used except as the name of a called function.
Some of these restricted specific intrinsic functions, e.g. FLOAT
,
provide a means for invoking a corresponding generic (REAL
in the case of FLOAT
)
with forced argument and result kinds.
Others, viz. CHAR
, ICHAR
, INT
, REAL
, and the lexical comparisons like LGE
,
have the same name as their generic functions, and it is not clear what purpose
is accomplished by the standard by defining them as specific functions.
Trigonometric elemental intrinsic functions, generic and (mostly) specific¶
All of these functions can be used as unrestricted specific names.
ACOS(REAL(k) X) > REAL(k)
ASIN(REAL(k) X) > REAL(k)
ATAN(REAL(k) X) > REAL(k)
ATAN(REAL(k) Y, REAL(k) X) > REAL(k) = ATAN2(Y, X)
ATAN2(REAL(k) Y, REAL(k) X) > REAL(k)
COS(REAL(k) X) > REAL(k)
COSH(REAL(k) X) > REAL(k)
SIN(REAL(k) X) > REAL(k)
SINH(REAL(k) X) > REAL(k)
TAN(REAL(k) X) > REAL(k)
TANH(REAL(k) X) > REAL(k)
These COMPLEX
versions of some of those functions, and the
inverse hyperbolic functions, cannot be used as specific names.
ACOS(COMPLEX(k) X) > COMPLEX(k)
ASIN(COMPLEX(k) X) > COMPLEX(k)
ATAN(COMPLEX(k) X) > COMPLEX(k)
ACOSH(REAL(k) X) > REAL(k)
ACOSH(COMPLEX(k) X) > COMPLEX(k)
ASINH(REAL(k) X) > REAL(k)
ASINH(COMPLEX(k) X) > COMPLEX(k)
ATANH(REAL(k) X) > REAL(k)
ATANH(COMPLEX(k) X) > COMPLEX(k)
COS(COMPLEX(k) X) > COMPLEX(k)
COSH(COMPLEX(k) X) > COMPLEX(k)
SIN(COMPLEX(k) X) > COMPLEX(k)
SINH(COMPLEX(k) X) > COMPLEX(k)
TAN(COMPLEX(k) X) > COMPLEX(k)
TANH(COMPLEX(k) X) > COMPLEX(k)
Nontrigonometric elemental intrinsic functions, generic and specific¶
These functions can be used as unrestricted specific names.
ABS(REAL(k) A) > REAL(k) = SIGN(A, 0.0)
AIMAG(COMPLEX(k) Z) > REAL(k) = Z%IM
AINT(REAL(k) A, KIND=k) > REAL(KIND)
ANINT(REAL(k) A, KIND=k) > REAL(KIND)
CONJG(COMPLEX(k) Z) > COMPLEX(k) = CMPLX(Z%RE, Z%IM)
DIM(REAL(k) X, REAL(k) Y) > REAL(k) = XMIN(X,Y)
DPROD(default REAL X, default REAL Y) > DOUBLE PRECISION = DBLE(X)*DBLE(Y)
EXP(REAL(k) X) > REAL(k)
INDEX(CHARACTER(k) STRING, CHARACTER(k) SUBSTRING, LOGICAL(any) BACK=.FALSE., KIND=KIND(0)) > INTEGER(KIND)
LEN(CHARACTER(k,n) STRING, KIND=KIND(0)) > INTEGER(KIND) = n
LOG(REAL(k) X) > REAL(k)
LOG10(REAL(k) X) > REAL(k)
MOD(INTEGER(k) A, INTEGER(k) P) > INTEGER(k) = AP*INT(A/P)
NINT(REAL(k) A, KIND=KIND(0)) > INTEGER(KIND)
SIGN(REAL(k) A, REAL(k) B) > REAL(k)
SQRT(REAL(k) X) > REAL(k) = X ** 0.5
These variants, however cannot be used as specific names without recourse to an alias from the following section:
ABS(INTEGER(k) A) > INTEGER(k) = SIGN(A, 0)
ABS(COMPLEX(k) A) > REAL(k) = HYPOT(A%RE, A%IM)
DIM(INTEGER(k) X, INTEGER(k) Y) > INTEGER(k) = XMIN(X,Y)
EXP(COMPLEX(k) X) > COMPLEX(k)
LOG(COMPLEX(k) X) > COMPLEX(k)
MOD(REAL(k) A, REAL(k) P) > REAL(k) = AP*INT(A/P)
SIGN(INTEGER(k) A, INTEGER(k) B) > INTEGER(k)
SQRT(COMPLEX(k) X) > COMPLEX(k)
Unrestricted specific aliases for some elemental intrinsic functions with distinct names¶
ALOG(REAL X) > REAL = LOG(X)
ALOG10(REAL X) > REAL = LOG10(X)
AMOD(REAL A, REAL P) > REAL = MOD(A, P)
CABS(COMPLEX A) = ABS(A)
CCOS(COMPLEX X) = COS(X)
CEXP(COMPLEX A) > COMPLEX = EXP(A)
CLOG(COMPLEX X) > COMPLEX = LOG(X)
CSIN(COMPLEX X) > COMPLEX = SIN(X)
CSQRT(COMPLEX X) > COMPLEX = SQRT(X)
CTAN(COMPLEX X) > COMPLEX = TAN(X)
DABS(DOUBLE PRECISION A) > DOUBLE PRECISION = ABS(A)
DACOS(DOUBLE PRECISION X) > DOUBLE PRECISION = ACOS(X)
DASIN(DOUBLE PRECISION X) > DOUBLE PRECISION = ASIN(X)
DATAN(DOUBLE PRECISION X) > DOUBLE PRECISION = ATAN(X)
DATAN2(DOUBLE PRECISION Y, DOUBLE PRECISION X) > DOUBLE PRECISION = ATAN2(Y, X)
DCOS(DOUBLE PRECISION X) > DOUBLE PRECISION = COS(X)
DCOSH(DOUBLE PRECISION X) > DOUBLE PRECISION = COSH(X)
DDIM(DOUBLE PRECISION X, DOUBLE PRECISION Y) > DOUBLE PRECISION = XMIN(X,Y)
DEXP(DOUBLE PRECISION X) > DOUBLE PRECISION = EXP(X)
DINT(DOUBLE PRECISION A) > DOUBLE PRECISION = AINT(A)
DLOG(DOUBLE PRECISION X) > DOUBLE PRECISION = LOG(X)
DLOG10(DOUBLE PRECISION X) > DOUBLE PRECISION = LOG10(X)
DMOD(DOUBLE PRECISION A, DOUBLE PRECISION P) > DOUBLE PRECISION = MOD(A, P)
DNINT(DOUBLE PRECISION A) > DOUBLE PRECISION = ANINT(A)
DSIGN(DOUBLE PRECISION A, DOUBLE PRECISION B) > DOUBLE PRECISION = SIGN(A, B)
DSIN(DOUBLE PRECISION X) > DOUBLE PRECISION = SIN(X)
DSINH(DOUBLE PRECISION X) > DOUBLE PRECISION = SINH(X)
DSQRT(DOUBLE PRECISION X) > DOUBLE PRECISION = SQRT(X)
DTAN(DOUBLE PRECISION X) > DOUBLE PRECISION = TAN(X)
DTANH(DOUBLE PRECISION X) > DOUBLE PRECISION = TANH(X)
IABS(INTEGER A) > INTEGER = ABS(A)
IDIM(INTEGER X, INTEGER Y) > INTEGER = XMIN(X,Y)
IDNINT(DOUBLE PRECISION A) > INTEGER = NINT(A)
ISIGN(INTEGER A, INTEGER B) > INTEGER = SIGN(A, B)
Generic elemental intrinsic functions without specific names¶
(No procedures after this point can be passed as actual arguments, used as pointer targets, or appear as specific procedures in generic interfaces.)
Elemental conversions¶
ACHAR(INTEGER(k) I, KIND=KIND('')) > CHARACTER(KIND,LEN=1)
CEILING(REAL() A, KIND=KIND(0)) > INTEGER(KIND)
CHAR(INTEGER(any) I, KIND=KIND('')) > CHARACTER(KIND,LEN=1)
CMPLX(COMPLEX(k) X, KIND=KIND(0.0D0)) > COMPLEX(KIND)
CMPLX(INTEGER or REAL or BOZ X, INTEGER or REAL or BOZ Y=0, KIND=KIND((0,0))) > COMPLEX(KIND)
DBLE(INTEGER or REAL or COMPLEX or BOZ A) = REAL(A, KIND=KIND(0.0D0))
EXPONENT(REAL(any) X) > default INTEGER
FLOOR(REAL(any) A, KIND=KIND(0)) > INTEGER(KIND)
IACHAR(CHARACTER(KIND=k,LEN=1) C, KIND=KIND(0)) > INTEGER(KIND)
ICHAR(CHARACTER(KIND=k,LEN=1) C, KIND=KIND(0)) > INTEGER(KIND)
INT(INTEGER or REAL or COMPLEX or BOZ A, KIND=KIND(0)) > INTEGER(KIND)
LOGICAL(LOGICAL(any) L, KIND=KIND(.TRUE.)) > LOGICAL(KIND)
REAL(INTEGER or REAL or COMPLEX or BOZ A, KIND=KIND(0.0)) > REAL(KIND)
Other generic elemental intrinsic functions without specific names¶
N.B. BESSEL_JN(N1, N2, X)
and BESSEL_YN(N1, N2, X)
are categorized
below with the transformational intrinsic functions.
BESSEL_J0(REAL(k) X) > REAL(k)
BESSEL_J1(REAL(k) X) > REAL(k)
BESSEL_JN(INTEGER(n) N, REAL(k) X) > REAL(k)
BESSEL_Y0(REAL(k) X) > REAL(k)
BESSEL_Y1(REAL(k) X) > REAL(k)
BESSEL_YN(INTEGER(n) N, REAL(k) X) > REAL(k)
ERF(REAL(k) X) > REAL(k)
ERFC(REAL(k) X) > REAL(k)
ERFC_SCALED(REAL(k) X) > REAL(k)
FRACTION(REAL(k) X) > REAL(k)
GAMMA(REAL(k) X) > REAL(k)
HYPOT(REAL(k) X, REAL(k) Y) > REAL(k) = SQRT(X*X+Y*Y) without spurious overflow
IMAGE_STATUS(INTEGER(any) IMAGE [, scalar TEAM_TYPE TEAM ]) > default INTEGER
IS_IOSTAT_END(INTEGER(any) I) > default LOGICAL
IS_IOSTAT_EOR(INTEGER(any) I) > default LOGICAL
LOG_GAMMA(REAL(k) X) > REAL(k)
MAX(INTEGER(k) ...) > INTEGER(k)
MAX(REAL(k) ...) > REAL(k)
MAX(CHARACTER(KIND=k) ...) > CHARACTER(KIND=k,LEN=MAX(LEN(...)))
MERGE(any type TSOURCE, same type FSOURCE, LOGICAL(any) MASK) > type of FSOURCE
MIN(INTEGER(k) ...) > INTEGER(k)
MIN(REAL(k) ...) > REAL(k)
MIN(CHARACTER(KIND=k) ...) > CHARACTER(KIND=k,LEN=MAX(LEN(...)))
MODULO(INTEGER(k) A, INTEGER(k) P) > INTEGER(k); P*result >= 0
MODULO(REAL(k) A, REAL(k) P) > REAL(k) = A  P*FLOOR(A/P)
NEAREST(REAL(k) X, REAL(any) S) > REAL(k)
OUT_OF_RANGE(INTEGER(any) X, scalar INTEGER or REAL(k) MOLD) > default LOGICAL
OUT_OF_RANGE(REAL(any) X, scalar REAL(k) MOLD) > default LOGICAL
OUT_OF_RANGE(REAL(any) X, scalar INTEGER(any) MOLD, scalar LOGICAL(any) ROUND=.FALSE.) > default LOGICAL
RRSPACING(REAL(k) X) > REAL(k)
SCALE(REAL(k) X, INTEGER(any) I) > REAL(k)
SET_EXPONENT(REAL(k) X, INTEGER(any) I) > REAL(k)
SPACING(REAL(k) X) > REAL(k)
Restricted specific aliases for elemental conversions &/or extrema with default intrinsic types¶
AMAX0(INTEGER ...) = REAL(MAX(...))
AMAX1(REAL ...) = MAX(...)
AMIN0(INTEGER...) = REAL(MIN(...))
AMIN1(REAL ...) = MIN(...)
DMAX1(DOUBLE PRECISION ...) = MAX(...)
DMIN1(DOUBLE PRECISION ...) = MIN(...)
FLOAT(INTEGER I) = REAL(I)
IDINT(DOUBLE PRECISION A) = INT(A)
IFIX(REAL A) = INT(A)
MAX0(INTEGER ...) = MAX(...)
MAX1(REAL ...) = INT(MAX(...))
MIN0(INTEGER ...) = MIN(...)
MIN1(REAL ...) = INT(MIN(...))
SNGL(DOUBLE PRECISION A) = REAL(A)
Generic elemental bit manipulation intrinsic functions¶
Many of these accept a typeless “BOZ” literal as an actual argument.
It is interpreted as having the kind of intrinsic INTEGER
type
as another argument, as if the typeless were implicitly wrapped
in a call to INT()
.
When multiple arguments can be either INTEGER
values or typeless
constants, it is forbidden for all of them to be typeless
constants if the result of the function is INTEGER
(i.e., only BGE
, BGT
, BLE
, and BLT
can have multiple
typeless arguments).
BGE(INTEGER(n1) or BOZ I, INTEGER(n2) or BOZ J) > default LOGICAL
BGT(INTEGER(n1) or BOZ I, INTEGER(n2) or BOZ J) > default LOGICAL
BLE(INTEGER(n1) or BOZ I, INTEGER(n2) or BOZ J) > default LOGICAL
BLT(INTEGER(n1) or BOZ I, INTEGER(n2) or BOZ J) > default LOGICAL
BTEST(INTEGER(n1) I, INTEGER(n2) POS) > default LOGICAL
DSHIFTL(INTEGER(k) I, INTEGER(k) or BOZ J, INTEGER(any) SHIFT) > INTEGER(k)
DSHIFTL(BOZ I, INTEGER(k), INTEGER(any) SHIFT) > INTEGER(k)
DSHIFTR(INTEGER(k) I, INTEGER(k) or BOZ J, INTEGER(any) SHIFT) > INTEGER(k)
DSHIFTR(BOZ I, INTEGER(k), INTEGER(any) SHIFT) > INTEGER(k)
IAND(INTEGER(k) I, INTEGER(k) or BOZ J) > INTEGER(k)
IAND(BOZ I, INTEGER(k) J) > INTEGER(k)
IBCLR(INTEGER(k) I, INTEGER(any) POS) > INTEGER(k)
IBITS(INTEGER(k) I, INTEGER(n1) POS, INTEGER(n2) LEN) > INTEGER(k)
IBSET(INTEGER(k) I, INTEGER(any) POS) > INTEGER(k)
IEOR(INTEGER(k) I, INTEGER(k) or BOZ J) > INTEGER(k)
IEOR(BOZ I, INTEGER(k) J) > INTEGER(k)
IOR(INTEGER(k) I, INTEGER(k) or BOZ J) > INTEGER(k)
IOR(BOZ I, INTEGER(k) J) > INTEGER(k)
ISHFT(INTEGER(k) I, INTEGER(any) SHIFT) > INTEGER(k)
ISHFTC(INTEGER(k) I, INTEGER(n1) SHIFT, INTEGER(n2) SIZE=BIT_SIZE(I)) > INTEGER(k)
LEADZ(INTEGER(any) I) > default INTEGER
MASKL(INTEGER(any) I, KIND=KIND(0)) > INTEGER(KIND)
MASKR(INTEGER(any) I, KIND=KIND(0)) > INTEGER(KIND)
MERGE_BITS(INTEGER(k) I, INTEGER(k) or BOZ J, INTEGER(k) or BOZ MASK) = IOR(IAND(I,MASK),IAND(J,NOT(MASK)))
MERGE_BITS(BOZ I, INTEGER(k) J, INTEGER(k) or BOZ MASK) = IOR(IAND(I,MASK),IAND(J,NOT(MASK)))
NOT(INTEGER(k) I) > INTEGER(k)
POPCNT(INTEGER(any) I) > default INTEGER
POPPAR(INTEGER(any) I) > default INTEGER = IAND(POPCNT(I), Z'1')
SHIFTA(INTEGER(k) I, INTEGER(any) SHIFT) > INTEGER(k)
SHIFTL(INTEGER(k) I, INTEGER(any) SHIFT) > INTEGER(k)
SHIFTR(INTEGER(k) I, INTEGER(any) SHIFT) > INTEGER(k)
TRAILZ(INTEGER(any) I) > default INTEGER
Character elemental intrinsic functions¶
See also INDEX
and LEN
above among the elemental intrinsic functions with
unrestricted specific names.
ADJUSTL(CHARACTER(k,LEN=n) STRING) > CHARACTER(k,LEN=n)
ADJUSTR(CHARACTER(k,LEN=n) STRING) > CHARACTER(k,LEN=n)
LEN_TRIM(CHARACTER(k,n) STRING, KIND=KIND(0)) > INTEGER(KIND) = n
LGE(CHARACTER(k,n1) STRING_A, CHARACTER(k,n2) STRING_B) > default LOGICAL
LGT(CHARACTER(k,n1) STRING_A, CHARACTER(k,n2) STRING_B) > default LOGICAL
LLE(CHARACTER(k,n1) STRING_A, CHARACTER(k,n2) STRING_B) > default LOGICAL
LLT(CHARACTER(k,n1) STRING_A, CHARACTER(k,n2) STRING_B) > default LOGICAL
SCAN(CHARACTER(k,n) STRING, CHARACTER(k,m) SET, LOGICAL(any) BACK=.FALSE., KIND=KIND(0)) > INTEGER(KIND)
VERIFY(CHARACTER(k,n) STRING, CHARACTER(k,m) SET, LOGICAL(any) BACK=.FALSE., KIND=KIND(0)) > INTEGER(KIND)
SCAN
returns the index of the first (or last, if BACK=.TRUE.
) character in STRING
that is present in SET
, or zero if none is.
VERIFY
is essentially the opposite: it returns the index of the first (or last) character
in STRING
that is not present in SET
, or zero if all are.
Transformational intrinsic functions¶
This category comprises a large collection of intrinsic functions that are collected together because they somehow transform their arguments in a way that prevents them from being elemental. All of them are pure, however.
Some general rules apply to the transformational intrinsic functions:
DIM
arguments are optional; if present, the actual argument must be a scalar integer of any kind.When an optional
DIM
argument is absent, or anARRAY
orMASK
argument is a vector, the result of the function is scalar; otherwise, the result is an array of the same shape as theARRAY
orMASK
argument with the dimensionDIM
removed from the shape.When a function takes an optional
MASK
argument, it must be conformable with itsARRAY
argument if it is present, and the mask can be any kind ofLOGICAL
. It can be scalar.The type
numeric
here can be any kind ofINTEGER
,REAL
, orCOMPLEX
.The type
relational
here can be any kind ofINTEGER
,REAL
, orCHARACTER
.The type
any
here denotes any intrinsic or derived type.The notation
(..)
denotes an array of any rank (but not an assumedrank array).
Logical reduction transformational intrinsic functions¶
ALL(LOGICAL(k) MASK(..) [, DIM ]) > LOGICAL(k)
ANY(LOGICAL(k) MASK(..) [, DIM ]) > LOGICAL(k)
COUNT(LOGICAL(any) MASK(..) [, DIM, KIND=KIND(0) ]) > INTEGER(KIND)
PARITY(LOGICAL(k) MASK(..) [, DIM ]) > LOGICAL(k)
Numeric reduction transformational intrinsic functions¶
IALL(INTEGER(k) ARRAY(..) [, DIM, MASK ]) > INTEGER(k)
IANY(INTEGER(k) ARRAY(..) [, DIM, MASK ]) > INTEGER(k)
IPARITY(INTEGER(k) ARRAY(..) [, DIM, MASK ]) > INTEGER(k)
NORM2(REAL(k) X(..) [, DIM ]) > REAL(k)
PRODUCT(numeric ARRAY(..) [, DIM, MASK ]) > numeric
SUM(numeric ARRAY(..) [, DIM, MASK ]) > numeric
NORM2
generalizes HYPOT
by computing SQRT(SUM(X*X))
while avoiding spurious overflows.
Extrema reduction transformational intrinsic functions¶
MAXVAL(relational(k) ARRAY(..) [, DIM, MASK ]) > relational(k)
MINVAL(relational(k) ARRAY(..) [, DIM, MASK ]) > relational(k)
Locational transformational intrinsic functions¶
When the optional DIM
argument is absent, the result is an INTEGER(KIND)
vector whose length is the rank of ARRAY
.
When the optional DIM
argument is present, the result is an INTEGER(KIND)
array of rank RANK(ARRAY)1
and shape equal to that of ARRAY
with
the dimension DIM
removed.
The optional BACK
argument is a scalar LOGICAL value of any kind.
When present and .TRUE.
, it causes the function to return the index
of the last occurence of the target or extreme value.
For FINDLOC
, ARRAY
may have any of the five intrinsic types, and VALUE
must a scalar value of a type for which ARRAY==VALUE
or ARRAY .EQV. VALUE
is an acceptable expression.
FINDLOC(intrinsic ARRAY(..), scalar VALUE [, DIM, MASK, KIND=KIND(0), BACK=.FALSE. ])
MAXLOC(relational ARRAY(..) [, DIM, MASK, KIND=KIND(0), BACK=.FALSE. ])
MINLOC(relational ARRAY(..) [, DIM, MASK, KIND=KIND(0), BACK=.FALSE. ])
Data rearrangement transformational intrinsic functions¶
The optional DIM
argument to these functions must be a scalar integer of
any kind, and it takes a default value of 1 when absent.
CSHIFT(any ARRAY(..), INTEGER(any) SHIFT(..) [, DIM ]) > same type/kind/shape as ARRAY
Either SHIFT
is scalar or RANK(SHIFT) == RANK(ARRAY)  1
and SHAPE(SHIFT)
is that of SHAPE(ARRAY)
with element DIM
removed.
EOSHIFT(any ARRAY(..), INTEGER(any) SHIFT(..) [, BOUNDARY, DIM ]) > same type/kind/shape as ARRAY
SHIFT
is scalar orRANK(SHIFT) == RANK(ARRAY)  1
andSHAPE(SHIFT)
is that ofSHAPE(ARRAY)
with elementDIM
removed.If
BOUNDARY
is present, it must have the same type and parameters asARRAY
.If
BOUNDARY
is absent,ARRAY
must be of an intrinsic type, and the defaultBOUNDARY
is the obvious0
,' '
, or.FALSE.
value ofKIND(ARRAY)
.If
BOUNDARY
is present, either it is scalar, orRANK(BOUNDARY) == RANK(ARRAY)  1
andSHAPE(BOUNDARY)
is that ofSHAPE(ARRAY)
with elementDIM
removed.
PACK(any ARRAY(..), LOGICAL(any) MASK(..)) > vector of same type and kind as ARRAY
MASK
is conformable withARRAY
and may be scalar.The length of the result vector is
COUNT(MASK)
ifMASK
is an array, elseSIZE(ARRAY)
ifMASK
is.TRUE.
, else zero.
PACK(any ARRAY(..), LOGICAL(any) MASK(..), any VECTOR(n)) > vector of same type, kind, and size as VECTOR
MASK
is conformable withARRAY
and may be scalar.VECTOR
has the same type and kind asARRAY
.VECTOR
must not be smaller than result ofPACK
with noVECTOR
argument.The leading elements of
VECTOR
are replaced with elements fromARRAY
as ifPACK
had been invoked withoutVECTOR
.
RESHAPE(any SOURCE(..), INTEGER(k) SHAPE(n) [, PAD(..), INTEGER(k2) ORDER(n) ]) > SOURCE array with shape SHAPE
If
ORDER
is present, it is a vector of the same size asSHAPE
, and contains a permutation.The element(s) of
PAD
are used to fill out the result onceSOURCE
has been consumed.
SPREAD(any SOURCE, DIM, scalar INTEGER(any) NCOPIES) > same type as SOURCE, rank=RANK(SOURCE)+1
TRANSFER(any SOURCE, any MOLD) > scalar if MOLD is scalar, else vector; same type and kind as MOLD
TRANSFER(any SOURCE, any MOLD, scalar INTEGER(any) SIZE) > vector(SIZE) of type and kind of MOLD
TRANSPOSE(any MATRIX(n,m)) > matrix(m,n) of same type and kind as MATRIX
The shape of the result of SPREAD
is the same as that of SOURCE
, with NCOPIES
inserted
at position DIM
.
UNPACK(any VECTOR(n), LOGICAL(any) MASK(..), FIELD) > type and kind of VECTOR, shape of MASK
FIELD
has same type and kind as VECTOR
and is conformable with MASK
.
Other transformational intrinsic functions¶
BESSEL_JN(INTEGER(n1) N1, INTEGER(n2) N2, REAL(k) X) > REAL(k) vector (MAX(N2N1+1,0))
BESSEL_YN(INTEGER(n1) N1, INTEGER(n2) N2, REAL(k) X) > REAL(k) vector (MAX(N2N1+1,0))
COMMAND_ARGUMENT_COUNT() > scalar default INTEGER
DOT_PRODUCT(LOGICAL(k) VECTOR_A(n), LOGICAL(k) VECTOR_B(n)) > LOGICAL(k) = ANY(VECTOR_A .AND. VECTOR_B)
DOT_PRODUCT(COMPLEX(any) VECTOR_A(n), numeric VECTOR_B(n)) = SUM(CONJG(VECTOR_A) * VECTOR_B)
DOT_PRODUCT(INTEGER(any) or REAL(any) VECTOR_A(n), numeric VECTOR_B(n)) = SUM(VECTOR_A * VECTOR_B)
MATMUL(numeric ARRAY_A(j), numeric ARRAY_B(j,k)) > numeric vector(k)
MATMUL(numeric ARRAY_A(j,k), numeric ARRAY_B(k)) > numeric vector(j)
MATMUL(numeric ARRAY_A(j,k), numeric ARRAY_B(k,m)) > numeric matrix(j,m)
MATMUL(LOGICAL(n1) ARRAY_A(j), LOGICAL(n2) ARRAY_B(j,k)) > LOGICAL vector(k)
MATMUL(LOGICAL(n1) ARRAY_A(j,k), LOGICAL(n2) ARRAY_B(k)) > LOGICAL vector(j)
MATMUL(LOGICAL(n1) ARRAY_A(j,k), LOGICAL(n2) ARRAY_B(k,m)) > LOGICAL matrix(j,m)
NULL([POINTER/ALLOCATABLE MOLD]) > POINTER
REDUCE(any ARRAY(..), function OPERATION [, DIM, LOGICAL(any) MASK(..), IDENTITY, LOGICAL ORDERED=.FALSE. ])
REPEAT(CHARACTER(k,n) STRING, INTEGER(any) NCOPIES) > CHARACTER(k,n*NCOPIES)
SELECTED_CHAR_KIND('DEFAULT' or 'ASCII' or 'ISO_10646' or ...) > scalar default INTEGER
SELECTED_INT_KIND(scalar INTEGER(any) R) > scalar default INTEGER
SELECTED_REAL_KIND([scalar INTEGER(any) P, scalar INTEGER(any) R, scalar INTEGER(any) RADIX]) > scalar default INTEGER
SHAPE(SOURCE, KIND=KIND(0)) > INTEGER(KIND)(RANK(SOURCE))
TRIM(CHARACTER(k,n) STRING) > CHARACTER(k)
The type and kind of the result of a numeric MATMUL
is the same as would result from
a multiplication of an element of ARRAY_A and an element of ARRAY_B.
The kind of the LOGICAL
result of a LOGICAL
MATMUL
is the same as would result
from an intrinsic .AND.
operation between an element of ARRAY_A
and an element
of ARRAY_B
.
Note that DOT_PRODUCT
with a COMPLEX
first argument operates on its complex conjugate,
but that MATMUL
with a COMPLEX
argument does not.
The MOLD
argument to NULL
may be omitted only in a context where the type of the pointer is known,
such as an initializer or pointer assignment statement.
At least one argument must be present in a call to SELECTED_REAL_KIND
.
An assumedrank array may be passed to SHAPE
, and if it is associated with an assumedsize array,
the last element of the result will be 1.
Coarray transformational intrinsic functions¶
FAILED_IMAGES([scalar TEAM_TYPE TEAM, KIND=KIND(0)]) > INTEGER(KIND) vector
GET_TEAM([scalar INTEGER(?) LEVEL]) > scalar TEAM_TYPE
IMAGE_INDEX(COARRAY, INTEGER(any) SUB(n) [, scalar TEAM_TYPE TEAM ]) > scalar default INTEGER
IMAGE_INDEX(COARRAY, INTEGER(any) SUB(n), scalar INTEGER(any) TEAM_NUMBER) > scalar default INTEGER
NUM_IMAGES([scalar TEAM_TYPE TEAM]) > scalar default INTEGER
NUM_IMAGES(scalar INTEGER(any) TEAM_NUMBER) > scalar default INTEGER
STOPPED_IMAGES([scalar TEAM_TYPE TEAM, KIND=KIND(0)]) > INTEGER(KIND) vector
TEAM_NUMBER([scalar TEAM_TYPE TEAM]) > scalar default INTEGER
THIS_IMAGE([COARRAY, DIM, scalar TEAM_TYPE TEAM]) > default INTEGER
The result of THIS_IMAGE
is a scalar if DIM
is present or if COARRAY
is absent,
and a vector whose length is the corank of COARRAY
otherwise.
Inquiry intrinsic functions¶
These are neither elemental nor transformational; all are pure.
Type inquiry intrinsic functions¶
All of these functions return constants. The value of the argument is not used, and may well be undefined.
BIT_SIZE(INTEGER(k) I(..)) > INTEGER(k)
DIGITS(INTEGER or REAL X(..)) > scalar default INTEGER
EPSILON(REAL(k) X(..)) > scalar REAL(k)
HUGE(INTEGER(k) X(..)) > scalar INTEGER(k)
HUGE(REAL(k) X(..)) > scalar of REAL(k)
KIND(intrinsic X(..)) > scalar default INTEGER
MAXEXPONENT(REAL(k) X(..)) > scalar default INTEGER
MINEXPONENT(REAL(k) X(..)) > scalar default INTEGER
NEW_LINE(CHARACTER(k,n) A(..)) > scalar CHARACTER(k,1) = CHAR(10)
PRECISION(REAL(k) or COMPLEX(k) X(..)) > scalar default INTEGER
RADIX(INTEGER(k) or REAL(k) X(..)) > scalar default INTEGER, always 2
RANGE(INTEGER(k) or REAL(k) or COMPLEX(k) X(..)) > scalar default INTEGER
TINY(REAL(k) X(..)) > scalar REAL(k)
Bound and size inquiry intrinsic functions¶
The results are scalar when DIM
is present, and a vector of length=(co)rank((CO)ARRAY
)
when DIM
is absent.
LBOUND(any ARRAY(..) [, DIM, KIND=KIND(0) ]) > INTEGER(KIND)
LCOBOUND(any COARRAY [, DIM, KIND=KIND(0) ]) > INTEGER(KIND)
SIZE(any ARRAY(..) [, DIM, KIND=KIND(0) ]) > INTEGER(KIND)
UBOUND(any ARRAY(..) [, DIM, KIND=KIND(0) ]) > INTEGER(KIND)
UCOBOUND(any COARRAY [, DIM, KIND=KIND(0) ]) > INTEGER(KIND)
Assumedrank arrays may be used with LBOUND
, SIZE
, and UBOUND
.
Object characteristic inquiry intrinsic functions¶
ALLOCATED(any type ALLOCATABLE ARRAY) > scalar default LOGICAL
ALLOCATED(any type ALLOCATABLE SCALAR) > scalar default LOGICAL
ASSOCIATED(any type POINTER POINTER [, same type TARGET]) > scalar default LOGICAL
COSHAPE(COARRAY, KIND=KIND(0)) > INTEGER(KIND) vector of length corank(COARRAY)
EXTENDS_TYPE_OF(A, MOLD) > default LOGICAL
IS_CONTIGUOUS(any data ARRAY(..)) > scalar default LOGICAL
PRESENT(OPTIONAL A) > scalar default LOGICAL
RANK(any data A) > scalar default INTEGER = 0 if A is scalar, SIZE(SHAPE(A)) if A is an array, rank if assumedrank
SAME_TYPE_AS(A, B) > scalar default LOGICAL
STORAGE_SIZE(any data A, KIND=KIND(0)) > INTEGER(KIND)
The arguments to EXTENDS_TYPE_OF
must be of extensible derived types or be unlimited polymorphic.
An assumedrank array may be used with IS_CONTIGUOUS
and RANK
.
Intrinsic subroutines¶
(TODO: complete these descriptions)
One elemental intrinsic subroutine¶
INTERFACE
SUBROUTINE MVBITS(FROM, FROMPOS, LEN, TO, TOPOS)
INTEGER(k1) :: FROM, TO
INTENT(IN) :: FROM
INTENT(INOUT) :: TO
INTEGER(k2), INTENT(IN) :: FROMPOS
INTEGER(k3), INTENT(IN) :: LEN
INTEGER(k4), INTENT(IN) :: TOPOS
END SUBROUTINE
END INTERFACE
Nonelemental intrinsic subroutines¶
CALL CPU_TIME(REAL INTENT(OUT) TIME)
The kind of TIME
is not specified in the standard.
CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])
All arguments are
OPTIONAL
andINTENT(OUT)
.DATE
,TIME
, andZONE
are scalar defaultCHARACTER
.VALUES
is a vector of at least 8 elements ofINTEGER(KIND >= 2)
.
CALL EVENT_QUERY(EVENT, COUNT [, STAT])
CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT, CMDMSG ])
CALL GET_COMMAND([COMMAND, LENGTH, STATUS, ERRMSG ])
CALL GET_COMMAND_ARGUMENT(NUMBER [, VALUE, LENGTH, STATUS, ERRMSG ])
CALL GET_ENVIRONMENT_VARIABLE(NAME [, VALUE, LENGTH, STATUS, TRIM_NAME, ERRMSG ])
CALL MOVE_ALLOC(ALLOCATABLE INTENT(INOUT) FROM, ALLOCATABLE INTENT(OUT) TO [, STAT, ERRMSG ])
CALL RANDOM_INIT(LOGICAL(k1) INTENT(IN) REPEATABLE, LOGICAL(k2) INTENT(IN) IMAGE_DISTINCT)
CALL RANDOM_NUMBER(REAL(k) INTENT(OUT) HARVEST(..))
CALL RANDOM_SEED([SIZE, PUT, GET])
CALL SYSTEM_CLOCK([COUNT, COUNT_RATE, COUNT_MAX])
Atomic intrinsic subroutines¶
CALL ATOMIC_ADD(ATOM, VALUE [, STAT=])
CALL ATOMIC_AND(ATOM, VALUE [, STAT=])
CALL ATOMIC_CAS(ATOM, OLD, COMPARE, NEW [, STAT=])
CALL ATOMIC_DEFINE(ATOM, VALUE [, STAT=])
CALL ATOMIC_FETCH_ADD(ATOM, VALUE, OLD [, STAT=])
CALL ATOMIC_FETCH_AND(ATOM, VALUE, OLD [, STAT=])
CALL ATOMIC_FETCH_OR(ATOM, VALUE, OLD [, STAT=])
CALL ATOMIC_FETCH_XOR(ATOM, VALUE, OLD [, STAT=])
CALL ATOMIC_OR(ATOM, VALUE [, STAT=])
CALL ATOMIC_REF(VALUE, ATOM [, STAT=])
CALL ATOMIC_XOR(ATOM, VALUE [, STAT=])
Collective intrinsic subroutines¶
CALL CO_BROADCAST
CALL CO_MAX
CALL CO_MIN
CALL CO_REDUCE
CALL CO_SUM
Inquiry Functions¶
ACCESS (GNU extension) is not supported on Windows. Otherwise:
CHARACTER(LEN=*) :: path = 'path/to/file'
IF (ACCESS(path, 'rwx')) &
...
Nonstandard intrinsics¶
PGI¶
AND, OR, XOR
LSHIFT, RSHIFT, SHIFT
ZEXT, IZEXT
COSD, SIND, TAND, ACOSD, ASIND, ATAND, ATAN2D
COMPL
DCMPLX
EQV, NEQV
INT8
JINT, JNINT, KNINT
LOC
Intel¶
DCMPLX(X,Y), QCMPLX(X,Y)
DREAL(DOUBLE COMPLEX A) > DOUBLE PRECISION
DFLOAT, DREAL
QEXT, QFLOAT, QREAL
DNUM, INUM, JNUM, KNUM, QNUM, RNUM  scan value from string
ZEXT
RAN, RANF
ILEN(I) = BIT_SIZE(I)
SIZEOF
MCLOCK, SECNDS
COTAN(X) = 1.0/TAN(X)
COSD, SIND, TAND, ACOSD, ASIND, ATAND, ATAN2D, COTAND  degrees
AND, OR, XOR
LSHIFT, RSHIFT
IBCHNG, ISHA, ISHC, ISHL, IXOR
IARG, IARGC, NARGS, NUMARG
BADDRESS, IADDR
CACHESIZE, EOF, FP_CLASS, INT_PTR_KIND, ISNAN, LOC
MALLOC
Library subroutine¶
CALL FDATE(TIME)
CALL GETLOG(USRNAME)
CALL GETENV(NAME [, VALUE, LENGTH, STATUS, TRIM_NAME, ERRMSG ])
Intrinsic Procedure Name Resolution¶
When the name of a procedure in a program is the same as the one of an intrinsic procedure, and nothing other than its usage allows to decide whether the procedure is the intrinsic or not (i.e, it does not appear in an INTRINSIC or EXTERNAL attribute statement, is not an use/host associated procedure…), Fortran 2018 standard section 19.5.1.4 point 6 rules that the procedure is established to be intrinsic if it is invoked as an intrinsic procedure.
In case the invocation would be an error if the procedure were the intrinsic (e.g. wrong argument number or type), the broad wording of the standard leaves two choices to the compiler: emit an error about the intrinsic invocation, or consider this is an external procedure and emit no error.
f18 will always consider this case to be the intrinsic and emit errors, unless the procedure is used as a function (resp. subroutine) and the intrinsic is a subroutine (resp. function). The table below gives some examples of decisions made by Fortran compilers in such case.
What is ACOS ? 
Bad intrinsic call 
External with warning 
External no warning 
Other error 


gfortran, nag, xlf, f18 
ifort 
nvfortran 


gfortran, nag, xlf, f18 
ifort 
nvfortran 


gfortran, nag, xlf, f18 
ifort 
nvfortran (keyword on implicit extrenal ) 


gfortran, nag, xlf, f18 
ifort 
nvfortran 


gfortran, nag, xlf, nvfortran, ifort, f18 
The rationale for f18 behavior is that when referring to a procedure with an argument number or type that does not match the intrinsic specification, it seems safer to block the rather likely case where the user is using the intrinsic the wrong way. In case the user wanted to refer to an external function, he can add an explicit EXTERNAL statement with no other consequences on the program. However, it seems rather unlikely that a user would confuse an intrinsic subroutine for a function and vice versa. Given no compiler is issuing an error here, changing the behavior might affect existing programs that omit the EXTERNAL attribute in such case.
Also note that in general, the standard gives the compiler the right to consider any procedure that is not explicitly external as a non standard intrinsic (section 4.2 point 4). So it is highly advised for the programmer to use EXTERNAL statements to prevent any ambiguity.
Intrinsic Procedure Support in f18¶
This section gives an overview of the support inside f18 libraries for the intrinsic procedures listed above. It may be outdated, refer to f18 code base for the actual support status.
Semantic Analysis¶
F18 semantic expression analysis phase detects intrinsic procedure references, validates the argument types and deduces the return types. This phase currently supports all the intrinsic procedures listed above but the ones in the table below.
Intrinsic Category 
Intrinsic Procedures Lacking Support 

Coarray intrinsic functions 
COSHAPE 
Object characteristic inquiry functions 
ALLOCATED, ASSOCIATED, EXTENDS_TYPE_OF, IS_CONTIGUOUS, PRESENT, RANK, SAME_TYPE, STORAGE_SIZE 
Type inquiry intrinsic functions 
BIT_SIZE, DIGITS, EPSILON, HUGE, KIND, MAXEXPONENT, MINEXPONENT, NEW_LINE, PRECISION, RADIX, RANGE, TINY 
Nonstandard intrinsic functions 
AND, OR, XOR, SHIFT, ZEXT, IZEXT, COSD, SIND, TAND, ACOSD, ASIND, ATAND, ATAN2D, COMPL, EQV, NEQV, INT8, JINT, JNINT, KNINT, QCMPLX, DREAL, DFLOAT, QEXT, QFLOAT, QREAL, DNUM, NUM, JNUM, KNUM, QNUM, RNUM, RAN, RANF, ILEN, SIZEOF, MCLOCK, SECNDS, COTAN, IBCHNG, ISHA, ISHC, ISHL, IXOR, IARG, IARGC, NARGS, GETPID, NUMARG, BADDRESS, IADDR, CACHESIZE, EOF, FP_CLASS, INT_PTR_KIND, ISNAN, MALLOC 
Intrinsic subroutines 
MVBITS (elemental), CPU_TIME, DATE_AND_TIME, EVENT_QUERY, EXECUTE_COMMAND_LINE, GET_COMMAND, GET_COMMAND_ARGUMENT, GET_ENVIRONMENT_VARIABLE, MOVE_ALLOC, RANDOM_INIT, RANDOM_NUMBER, RANDOM_SEED, SIGNAL, SLEEP, SYSTEM, SYSTEM_CLOCK 
Atomic intrinsic subroutines 
ATOMIC_ADD 
Collective intrinsic subroutines 
CO_REDUCE 
Library subroutines 
FDATE, GETLOG, GETENV 
Intrinsic Function Folding¶
Fortran Constant Expressions can contain references to a certain number of intrinsic functions (see Fortran 2018 standard section 10.1.12 for more details). Constant Expressions may be used to define kind arguments. Therefore, the semantic expression analysis phase must be able to fold references to intrinsic functions listed in section 10.1.12.
F18 intrinsic function folding is either performed by implementations directly operating on f18 scalar types or by using host runtime functions and host hardware types. F18 supports folding elemental intrinsic functions over arrays when an implementation is provided for the scalars (regardless of whether it is using host hardware types or not). The status of intrinsic function folding support is given in the subsections below.
Intrinsic Functions with Host Independent Folding Support¶
Implementations using f18 scalar types enables folding intrinsic functions on any host and with any possible type kind supported by f18. The intrinsic functions listed below are folded using host independent implementations.
Return Type 
Intrinsic Functions with Host Independent Folding Support 

INTEGER 
ABS(INTEGER(k)), DIM(INTEGER(k), INTEGER(k)), DSHIFTL, DSHIFTR, IAND, IBCLR, IBSET, IEOR, INT, IOR, ISHFT, KIND, LEN, LEADZ, MASKL, MASKR, MERGE_BITS, POPCNT, POPPAR, SHIFTA, SHIFTL, SHIFTR, TRAILZ 
REAL 
ABS(REAL(k)), ABS(COMPLEX(k)), AIMAG, AINT, DPROD, REAL 
COMPLEX 
CMPLX, CONJG 
LOGICAL 
BGE, BGT, BLE, BLT 
Intrinsic Functions with Host Dependent Folding Support¶
Implementations using the host runtime may not be available for all supported f18 types depending on the host hardware types and the libraries available on the host. The actual support on a host depends on what the host hardware types are. The list below gives the functions that are folded using host runtime and the related C/C++ types. F18 automatically detects if these types match an f18 scalar type. If so, folding of the intrinsic functions will be possible for the related f18 scalar type, otherwise an error message will be produced by f18 when attempting to fold related intrinsic functions.
C/C++ Host Type 
Intrinsic Functions with Host Standard C++ Library Based Folding Support 

float, double and long double 
ACOS, ACOSH, ASINH, ATAN, ATAN2, ATANH, COS, COSH, ERF, ERFC, EXP, GAMMA, HYPOT, LOG, LOG10, LOG_GAMMA, MOD, SIN, SQRT, SINH, SQRT, TAN, TANH 
std::complex for float, double and long double 
ACOS, ACOSH, ASIN, ASINH, ATAN, ATANH, COS, COSH, EXP, LOG, SIN, SINH, SQRT, TAN, TANH 
On top of the default usage of C++ standard library functions for folding described
in the table above, it is possible to compile f18 evaluate library with
libpgmath
so that it can be used for folding. To do so, one must have a compiled version
of the libpgmath library available on the host and add
DLIBPGMATH_DIR=<path to the compiled shared libpgmath library>
to the f18 cmake command.
Libpgmath comes with real and complex functions that replace C++ standard library float and double functions to fold all the intrinsic functions listed in the table above. It has no long double versions. If the host long double matches an f18 scalar type, C++ standard library functions will still be used for folding expressions with this scalar type. Libpgmath adds the possibility to fold the following functions for f18 real scalar types related to host float and double types.
C/C++ Host Type 
Additional Intrinsic Function Folding Support with Libpgmath (Optional) 

float and double 
BESSEL_J0, BESSEL_J1, BESSEL_JN (elemental only), BESSEL_Y0, BESSEL_Y1, BESSEL_Yn (elemental only), ERFC_SCALED 
Libpgmath comes in three variants (precise, relaxed and fast). So far, only the precise version is used for intrinsic function folding in f18. It guarantees the greatest numerical precision.
Intrinsic Functions with Missing Folding Support¶
The following intrinsic functions are allowed in constant expressions but f18 is not yet able to fold them. Note that there might be constraints on the arguments so that these intrinsics can be used in constant expressions (see section 10.1.12 of Fortran 2018 standard).
ALL, ACHAR, ADJUSTL, ADJUSTR, ANINT, ANY, BESSEL_JN (transformational only), BESSEL_YN (transformational only), BTEST, CEILING, CHAR, COUNT, CSHIFT, DOT_PRODUCT, DIM (REAL only), DOT_PRODUCT, EOSHIFT, FINDLOC, FLOOR, FRACTION, HUGE, IACHAR, IALL, IANY, IPARITY, IBITS, ICHAR, IMAGE_STATUS, INDEX, ISHFTC, IS_IOSTAT_END, IS_IOSTAT_EOR, LBOUND, LEN_TRIM, LGE, LGT, LLE, LLT, LOGICAL, MATMUL, MAX, MAXLOC, MAXVAL, MERGE, MIN, MINLOC, MINVAL, MOD (INTEGER only), MODULO, NEAREST, NINT, NORM2, NOT, OUT_OF_RANGE, PACK, PARITY, PRODUCT, REPEAT, REDUCE, RESHAPE, RRSPACING, SCAN, SCALE, SELECTED_CHAR_KIND, SELECTED_INT_KIND, SELECTED_REAL_KIND, SET_EXPONENT, SHAPE, SIGN, SIZE, SPACING, SPREAD, SUM, TINY, TRANSFER, TRANSPOSE, TRIM, UBOUND, UNPACK, VERIFY.
Coarray, non standard, IEEE and ISO_C_BINDINGS intrinsic functions that can be used in constant expressions have currently no folding support at all.
Standard Intrinsics: EXECUTE_COMMAND_LINE¶
Usage and Info¶
Standard: Fortran 2008 and later, specified in subclause 16.9.73
Class: Subroutine
Syntax:
CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT, CMDMSG ])
Arguments:
Argument 
Description 


Shall be a default CHARACTER scalar. 

(Optional) Shall be a default LOGICAL scalar. 

(Optional) Shall be an INTEGER with kind greater than or equal to 4. 

(Optional) Shall be an INTEGER with kind greater than or equal to 2. 

(Optional) Shall be a CHARACTER scalar of the default kind. 
Implementation Specifics¶
COMMAND
:¶
Must be preset.
WAIT
:¶
If set to
false
, the command is executed asynchronously.If not preset or set to
true
, it is executed synchronously.Synchronous execution is achieved by passing the command into
std::system
on all systems.Asynchronous execution is achieved by calling
fork()
on POSIXcompatible systems orCreateProcess()
on Windows.
EXITSTAT
:¶
Synchronous execution:
Inferred by the return value of
std::system(cmd)
.On POSIXcompatible systems: return value is first passed into
WEXITSTATUS(status)
, then assigned toEXITSTAT
.On Windows, the value is directly assigned as the return value of
std::system()
.
Asynchronous execution:
Value is not modified.
CMDSTAT
:¶
Synchronous execution:
2:
ASYNC_NO_SUPPORT_ERR
 No error condition occurs, butWAIT
is present with the valuefalse
, and the processor does not support asynchronous execution.1:
NO_SUPPORT_ERR
 The processor does not support command line execution. (system returns 1 with errnoENOENT
)0:
CMD_EXECUTED
 Command executed with no error.+ (positive value): An error condition occurs.
1:
FORK_ERR
 Fork Error (occurs only on POSIXcompatible systems).2:
EXECL_ERR
 Execution Error (system returns 1 with other errno).3:
COMMAND_EXECUTION_ERR
 Invalid Command Error (exit code 1).4:
COMMAND_CANNOT_EXECUTE_ERR
 Command Cannot Execute Error (Linux exit code 126).5:
COMMAND_NOT_FOUND_ERR
 Command Not Found Error (Linux exit code 127).6:
INVALID_CL_ERR
 Invalid Command Line Error (covers all other nonzero exit codes).7:
SIGNAL_ERR
 Signal error (either stopped or killed by signal, occurs only on POSIXcompatible systems).
Asynchronous execution:
0 will always be assigned.
CMDMSG
:¶
Synchronous execution:
If an error condition occurs, it is assigned an explanatory message; otherwise, it remains unchanged.
If a condition occurs that would assign a nonzero value to
CMDSTAT
but theCMDSTAT
variable is not present, error termination is initiated (applies to both POSIXcompatible systems and Windows).
Asynchronous execution:
The value is unchanged.
If a condition occurs that would assign a nonzero value to
CMDSTAT
but theCMDSTAT
variable is not present, error termination is initiated.On POSIXcompatible systems, the child process (async process) will be terminated with no effect on the parent process (continues).
On Windows, error termination is not initiated.
NonStandard Intrinsics: ETIME¶
Description¶
ETIME(VALUES, TIME)
returns the number of seconds of runtime since the start of the process’s execution in TIME. VALUES returns the user and system components of this time in VALUES(1)
and VALUES(2)
respectively. TIME is equal to VALUES(1) + VALUES(2)
.
On some systems, the underlying timings are represented using types with sufficiently small limits that overflows (wrap around) are possible, such as 32bit types. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program.
This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.
VALUES and TIME are INTENT(OUT)
and provide the following:

User time in seconds. 

System time in seconds. 

Run time since start in seconds. 
Usage and Info¶
Standard: GNU extension
Class: Subroutine, function
Syntax:
CALL ETIME(VALUES, TIME)
Arguments:
Return value Elapsed time in seconds since the start of program execution.
Argument 
Description 


The type shall be REAL(4), DIMENSION(2). 

The type shall be REAL(4). 
Example¶
Here is an example usage from Gfortran ETIME
program test_etime
integer(8) :: i, j
real, dimension(2) :: tarray
real :: result
call ETIME(tarray, result)
print *, result
print *, tarray(1)
print *, tarray(2)
do i=1,100000000 ! Just a delay
j = i * i  i
end do
call ETIME(tarray, result)
print *, result
print *, tarray(1)
print *, tarray(2)
end program test_etime
NonStandard Intrinsics: GETCWD¶
Description¶
GETCWD(C, STATUS)
returns current working directory.
This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.
C and STATUS are INTENT(OUT)
and provide the following:

Current work directory. The type shall be 

(Optional) Status flag. Returns 0 on success, a system specific and nonzero error code otherwise. The type shall be 
Usage and Info¶
Standard: GNU extension
Class: Subroutine, function
Syntax:
CALL GETCWD(C, STATUS)
,STATUS = GETCWD(C)
Example¶
PROGRAM example_getcwd
CHARACTER(len=255) :: cwd
INTEGER :: status
CALL getcwd(cwd, status)
PRINT *, cwd
PRINT *, status
END PROGRAM
Nonstandard Intrinsics: RENAME¶
RENAME(OLD, NEW[, STATUS])
renames/moves a file on the filesystem.
This intrinsic is provided in both subroutine and function form; however, only one form can be used in any given program unit.
Usage and Info¶
Standard: GNU extension
Class: Subroutine, function
Syntax:
CALL RENAME(SRC, DST[, STATUS])
Arguments:
Return value status code (0: success, nonzero for errors)
Argument 
Description 


Source path 

Destination path 

Status code (for subroutine form) 
The status code returned by both the subroutine and function form corresponds to the value of errno
if the invocation of rename(2)
was not successful.
Example¶
Function form:
program rename_func
implicit none
integer :: status
status = rename('src', 'dst')
print *, 'status:', status
status = rename('dst', 'src')
print *, 'status:', status
end program rename_func
Subroutine form:
program rename_proc
implicit none
integer :: status
call rename('src', 'dst', status)
print *, 'status:', status
call rename('dst', 'src')
end program rename_proc
Nonstandard Intrinsics: SECOND¶
This intrinsic is an alias for CPU_TIME
: supporting both a subroutine and a
function form.
Usage and Info¶
Standard: GNU extension
Class: Subroutine, function
Syntax:
CALL SECOND(TIME)
orTIME = SECOND()
Arguments:
TIME
 a REAL value into which the elapsed CPU time in seconds is writtenRETURN value: same as TIME argument