intrinsic.texi

理解和实践操作系统的一本好书

@item (C) If @var{TGT} is present and an array target, the result is true if
@var{TGT} and @var{PTR} have the same shape, are not 0 sized arrays, are
arrays whose elements are not 0 sized storage sequences, and @var{TGT} and
@var{PTR} occupy the same storage units in array element order.
As in case(B), the result is false, if @var{PTR} is disassociated.
@item (D) If @var{TGT} is present and an scalar pointer, the result is true if
target associated with @var{PTR} and the target associated with @var{TGT}
are not 0 sized storage sequences and occupy the same storage units.
The result is false, if either @var{TGT} or @var{PTR} is disassociated.
@item (E) If @var{TGT} is present and an array pointer, the result is true if
target associated with @var{PTR} and the target associated with @var{TGT}
have the same shape, are not 0 sized arrays, are arrays whose elements are
not 0 sized storage sequences, and @var{TGT} and @var{PTR} occupy the same
storage units in array element order.
The result is false, if either @var{TGT} or @var{PTR} is disassociated.
@end table

@item @emph{Example}:
@smallexample
program test_associated
   implicit none
   real, target  :: tgt(2) = (/1., 2./)
   real, pointer :: ptr(:)
   ptr => tgt
   if (associated(ptr)     .eqv. .false.) call abort
   if (associated(ptr,tgt) .eqv. .false.) call abort
end program test_associated
@end smallexample

@item @emph{See also}:
@ref{NULL}
@end table



@node ATAN
@section @code{ATAN} --- Arctangent function 
@fnindex ATAN
@fnindex DATAN
@cindex trigonometric function, tangent, inverse
@cindex tangent, inverse

@table @asis
@item @emph{Description}:
@code{ATAN(X)} computes the arctangent of @var{X}.

@item @emph{Standard}:
F77 and later

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = ATAN(X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{X} @tab The type shall be @code{REAL(*)}.
@end multitable

@item @emph{Return value}:
The return value is of type @code{REAL(*)} and it lies in the
range @math{ - \pi / 2 \leq \atan (x) \leq \pi / 2}.

@item @emph{Example}:
@smallexample
program test_atan
  real(8) :: x = 2.866_8
  x = atan(x)
end program test_atan
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name            @tab Argument          @tab Return type       @tab Standard
@item @code{DATAN(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab F77 and later
@end multitable

@item @emph{See also}:
Inverse function: @ref{TAN}

@end table



@node ATAN2
@section @code{ATAN2} --- Arctangent function 
@fnindex ATAN2
@fnindex DATAN2
@cindex trigonometric function, tangent, inverse
@cindex tangent, inverse

@table @asis
@item @emph{Description}:
@code{ATAN2(Y,X)} computes the arctangent of the complex number
@math{X + i Y}.

@item @emph{Standard}:
F77 and later

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = ATAN2(Y,X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{Y} @tab The type shall be @code{REAL(*)}.
@item @var{X} @tab The type and kind type parameter shall be the same as @var{Y}.
If @var{Y} is zero, then @var{X} must be nonzero.
@end multitable

@item @emph{Return value}:
The return value has the same type and kind type parameter as @var{Y}.
It is the principal value of the complex number @math{X + i Y}.  If
@var{X} is nonzero, then it lies in the range @math{-\pi \le \atan (x) \leq \pi}.
The sign is positive if @var{Y} is positive.  If @var{Y} is zero, then
the return value is zero if @var{X} is positive and @math{\pi} if @var{X}
is negative.  Finally, if @var{X} is zero, then the magnitude of the result
is @math{\pi/2}.

@item @emph{Example}:
@smallexample
program test_atan2
  real(4) :: x = 1.e0_4, y = 0.5e0_4
  x = atan2(y,x)
end program test_atan2
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name            @tab Argument          @tab Return type    @tab Standard
@item @code{DATAN2(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab F77 and later
@end multitable
@end table



@node ATANH
@section @code{ATANH} --- Hyperbolic arctangent function
@fnindex ASINH
@fnindex DASINH
@cindex area hyperbolic tangent
@cindex hyperbolic arctangent
@cindex hyperbolic function, tangent, inverse
@cindex tangent, hyperbolic, inverse

@table @asis
@item @emph{Description}:
@code{ATANH(X)} computes the hyperbolic arctangent of @var{X} (inverse
of @code{TANH(X)}).

@item @emph{Standard}:
GNU extension

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = ATANH(X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{X} @tab The type shall be @code{REAL(*)} with a magnitude
that is less than or equal to one.
@end multitable

@item @emph{Return value}:
The return value is of type @code{REAL(*)} and it lies in the
range @math{-\infty \leq \atanh(x) \leq \infty}.

@item @emph{Example}:
@smallexample
PROGRAM test_atanh
  REAL, DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
  WRITE (*,*) ATANH(x)
END PROGRAM
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name             @tab Argument          @tab Return type       @tab Standard
@item @code{DATANH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
@end multitable

@item @emph{See also}:
Inverse function: @ref{TANH}
@end table



@node BESJ0
@section @code{BESJ0} --- Bessel function of the first kind of order 0
@fnindex BESJ0
@fnindex DBESJ0
@cindex Bessel function, first kind

@table @asis
@item @emph{Description}:
@code{BESJ0(X)} computes the Bessel function of the first kind of order 0
of @var{X}.

@item @emph{Standard}:
GNU extension

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = BESJ0(X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{X} @tab The type shall be @code{REAL(*)}, and it shall be scalar.
@end multitable

@item @emph{Return value}:
The return value is of type @code{REAL(*)} and it lies in the
range @math{ - 0.4027... \leq Bessel (0,x) \leq 1}.

@item @emph{Example}:
@smallexample
program test_besj0
  real(8) :: x = 0.0_8
  x = besj0(x)
end program test_besj0
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name            @tab Argument          @tab Return type       @tab Standard
@item @code{DBESJ0(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}   @tab GNU extension
@end multitable
@end table



@node BESJ1
@section @code{BESJ1} --- Bessel function of the first kind of order 1
@fnindex BESJ1
@fnindex DBESJ1
@cindex Bessel function, first kind

@table @asis
@item @emph{Description}:
@code{BESJ1(X)} computes the Bessel function of the first kind of order 1
of @var{X}.

@item @emph{Standard}:
GNU extension

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = BESJ1(X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{X} @tab The type shall be @code{REAL(*)}, and it shall be scalar.
@end multitable

@item @emph{Return value}:
The return value is of type @code{REAL(*)} and it lies in the
range @math{ - 0.5818... \leq Bessel (0,x) \leq 0.5818 }.

@item @emph{Example}:
@smallexample
program test_besj1
  real(8) :: x = 1.0_8
  x = besj1(x)
end program test_besj1
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name            @tab Argument          @tab Return type       @tab Standard
@item @code{DBESJ1(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
@end multitable
@end table



@node BESJN
@section @code{BESJN} --- Bessel function of the first kind
@fnindex BESJN
@fnindex DBESJN
@cindex Bessel function, first kind

@table @asis
@item @emph{Description}:
@code{BESJN(N, X)} computes the Bessel function of the first kind of order
@var{N} of @var{X}.

If both arguments are arrays, their ranks and shapes shall conform.

@item @emph{Standard}:
GNU extension

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = BESJN(N, X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{N} @tab Shall be a scalar or an array of type  @code{INTEGER(*)}.
@item @var{X} @tab Shall be a scalar or an array of type  @code{REAL(*)}.
@end multitable

@item @emph{Return value}:
The return value is a scalar of type @code{REAL(*)}.

@item @emph{Example}:
@smallexample
program test_besjn
  real(8) :: x = 1.0_8
  x = besjn(5,x)
end program test_besjn
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name             @tab Argument            @tab Return type       @tab Standard
@item @code{DBESJN(X)} @tab @code{INTEGER(*) N} @tab @code{REAL(8)}    @tab GNU extension
@item                  @tab @code{REAL(8) X}    @tab                   @tab
@end multitable
@end table



@node BESY0
@section @code{BESY0} --- Bessel function of the second kind of order 0
@fnindex BESY0
@fnindex DBESY0
@cindex Bessel function, second kind

@table @asis
@item @emph{Description}:
@code{BESY0(X)} computes the Bessel function of the second kind of order 0
of @var{X}.

@item @emph{Standard}:
GNU extension

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = BESY0(X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{X} @tab The type shall be @code{REAL(*)}, and it shall be scalar.
@end multitable

@item @emph{Return value}:
The return value is a scalar of type @code{REAL(*)}.

@item @emph{Example}:
@smallexample
program test_besy0
  real(8) :: x = 0.0_8
  x = besy0(x)
end program test_besy0
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name            @tab Argument          @tab Return type       @tab Standard
@item @code{DBESY0(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
@end multitable
@end table



@node BESY1
@section @code{BESY1} --- Bessel function of the second kind of order 1
@fnindex BESY1
@fnindex DBESY1
@cindex Bessel function, second kind

@table @asis
@item @emph{Description}:
@code{BESY1(X)} computes the Bessel function of the second kind of order 1
of @var{X}.

@item @emph{Standard}:
GNU extension

@item @emph{Class}:
Elemental function

@item @emph{Syntax}:
@code{RESULT = BESY1(X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{X} @tab The type shall be @code{REAL(*)}, and it shall be scalar.
@end multitable

@item @emph{Return value}:
The return value is a scalar of type @code{REAL(*)}.

@item @emph{Example}:
@smallexample
program test_besy1
  real(8) :: x = 1.0_8
  x = besy1(x)
end program test_besy1
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .20 .20 .20 .25
@item Name            @tab Argument          @tab Return type       @tab Standard
@item @code{DBESY1(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
@end multitable
@end table



@node BESYN
@section @code{BESYN} --- Bessel function of the second kind
@fnindex BESYN
@fnindex DBESYN
@cindex Bessel function, second kind

@table @asis
@item @emph{Description}: