intrinsic.texi

gcc-fortran,linux使用fortran的编译软件。很好用的。

@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .24 .24 .24 .24
@item Name            @tab Argument          @tab Return type       @tab Option
@item @code{DATAN(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab f95, gnu
@end multitable
@end table



@node ATAN2
@section @code{ATAN2} --- Arctangent function 
@findex @code{ATAN2} intrinsic
@findex @code{DATAN2} intrinsic
@cindex arctangent

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

@item @emph{Option}:
f95, gnu

@item @emph{Class}:
elemental function

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

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@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 principle value of the complex number @math{X + i Y}.  If
@var{X} is nonzero, then it lies in the range @math{-\pi \le \arccos (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 .24 .24 .24 .24
@item Name            @tab Argument          @tab Return type    @tab Option
@item @code{DATAN2(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab f95, gnu
@end multitable
@end table



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

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

@item @emph{Option}:
gnu

@item @emph{Class}:
elemental function

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

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@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 .24 .24 .24 .24
@item Name            @tab Argument          @tab Return type       @tab Option
@item @code{DBESJ0(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab gnu
@end multitable
@end table



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

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

@item @emph{Option}:
gnu

@item @emph{Class}:
elemental function

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

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@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 .24 .24 .24 .24
@item Name            @tab Argument          @tab Return type       @tab Option
@item @code{DBESJ1(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab gnu
@end multitable
@end table



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

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

@item @emph{Option}:
gnu

@item @emph{Class}:
elemental function

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

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@item @var{N} @tab The type shall be @code{INTEGER(*)}, and it shall be scalar.
@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_besjn
  real(8) :: x = 1.0_8
  x = besjn(5,x)
end program test_besjn
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .24 .24 .24 .24
@item Name             @tab Argument            @tab Return type       @tab Option
@item @code{DBESJN(X)} @tab @code{INTEGER(*) N} @tab @code{REAL(8)}    @tab gnu
@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
@findex @code{BESY0} intrinsic
@findex @code{DBESY0} intrinsic
@cindex Bessel

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

@item @emph{Option}:
gnu

@item @emph{Class}:
elemental function

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

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@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 .24 .24 .24 .24
@item Name            @tab Argument          @tab Return type       @tab Option
@item @code{DBESY0(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab gnu
@end multitable
@end table



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

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

@item @emph{Option}:
gnu

@item @emph{Class}:
elemental function

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

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@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 .24 .24 .24 .24
@item Name            @tab Argument          @tab Return type       @tab Option
@item @code{DBESY1(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab gnu
@end multitable
@end table



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

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

@item @emph{Option}:
gnu

@item @emph{Class}:
elemental function

@item @emph{Syntax}:
@code{Y = BESYN(N, X)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@item @var{N} @tab The type shall be @code{INTEGER(*)}, and it shall be scalar.
@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_besyn
  real(8) :: x = 1.0_8
  x = besyn(5,x)
end program test_besyn
@end smallexample

@item @emph{Specific names}:
@multitable @columnfractions .24 .24 .24 .24
@item Name               @tab Argument            @tab Return type     @tab Option
@item @code{DBESYN(N,X)} @tab @code{INTEGER(*) N} @tab @code{REAL(8)}  @tab gnu
@item                    @tab @code{REAL(8)    X} @tab                 @tab 
@end multitable
@end table



@node BIT_SIZE
@section @code{BIT_SIZE} --- Bit size inquiry function
@findex @code{BIT_SIZE} intrinsic
@cindex bit_size

@table @asis
@item @emph{Description}:
@code{BIT_SIZE(I)} returns the number of bits (integer precision plus sign bit)
represented by the type of @var{I}.

@item @emph{Option}:
f95, gnu

@item @emph{Class}:
elemental function

@item @emph{Syntax}:
@code{I = BIT_SIZE(I)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@item @var{I} @tab The type shall be @code{INTEGER(*)}.
@end multitable

@item @emph{Return value}:
The return value is of type @code{INTEGER(*)}

@item @emph{Example}:
@smallexample
program test_bit_size
    integer :: i = 123
    integer :: size
    size = bit_size(i)
    print *, size
end program test_bit_size
@end smallexample
@end table



@node BTEST
@section @code{BTEST} --- Bit test function
@findex @code{BTEST} intrinsic
@cindex BTEST

@table @asis
@item @emph{Description}:
@code{BTEST(I,POS)} returns logical @code{.TRUE.} if the bit at @var{POS}
in @var{I} is set.

@item @emph{Option}:
f95, gnu

@item @emph{Class}:
elemental function

@item @emph{Syntax}:
@code{I = BTEST(I,POS)}

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@item @var{I} @tab The type shall be @code{INTEGER(*)}.
@item @var{POS} @tab The type shall be @code{INTEGER(*)}.
@end multitable

@item @emph{Return value}:
The return value is of type @code{LOGICAL}

@item @emph{Example}:
@smallexample
program test_btest
    integer :: i = 32768 + 1024 + 64
    integer :: pos
    logical :: bool
    do pos=0,16
        bool = btest(i, pos) 
        print *, pos, bool
    end do
end program test_btest
@end smallexample
@end table



@node CEILING
@section @code{CEILING} --- Integer ceiling function
@findex @code{CEILING} intrinsic
@cindex CEILING

@table @asis
@item @emph{Description}:
@code{CEILING(X)} returns the least integer greater than or equal to @var{X}.

@item @emph{Option}:
f95, gnu

@item @emph{Class}:
elemental function

@item @emph{Syntax}:
@code{I = CEILING(X[,KIND])}

@item @emph{Arguments}:
@multitable @columnfractions .15 .80
@item @var{X} @tab The type shall be @code{REAL(*)}.
@item @var{KIND} @tab Optional scaler integer initialization expression.
@end multitable

@item @emph{Return value}:
The return value is of type @code{INTEGER(KIND)}

@item @emph{Example}:
@smallexample
program test_ceiling
    real :: x = 63.29
    real :: y = -63.59
    print *, ceiling(x) ! returns 64
    print *, ceiling(y) ! returns -63
end program test_ceiling
@end smallexample
@end table



@node CHAR
@section @code{CHAR} --- Character conversion function
@findex @code{CHAR} intrinsic
@cindex CHAR

@table @asis
@item @emph{Description}:
@code{CHAR(I,[KIND])} returns the character represented by the integer @var{I}.

@item @emph{Option}:
f95, gnu

@item @emph{Class}:
elemental function