alog(3I)

NAME
     LOG, ALOG, DLOG, QLOG, CLOG, CDLOG, CQLOG - Computes natural logarithm

SYNOPSIS
     LOG ([X=]x)
     ALOG ([X=]x)
     DLOG ([X=]x)
     QLOG ([X=]x)
     CLOG ([X=]x)
     CDLOG ([X=]x)
     CQLOG ([X=]x)

IMPLEMENTATION
     UNICOS, UNICOS/mk, IRIX systems

     CF90, MIPSpro 7 Fortran 90, MIPSpro Fortran 77

STANDARDS
     Fortran

     Fortran extensions:  QLOG, CDLOG, CQLOG

DESCRIPTION
     LOG is the generic function name; the others are specifics.  These are
     elemental intrinsic functions.  They accept the following argument:

     x         For ALOG, DLOG, and QLOG, x must be greater than zero and of
               type real.  For CLOG, CDLOG, and CQLOG, x must be of type
               complex and not equal to (0.,0.).  The type and kind type of
               x is identical to the type and kind type of the return
               value.  See the RETURN VALUES section for information on
               input data types and return values.

     Vector versions of these intrinsics exist on some systems.  Vector
     versions of ALOG, DLOG, CLOG, and CDLOG exist on UNICOS and UNICOS/mk
     systems.  On UNICOS/mk systems, the vector versions of these
     intrinsics are used when -O vector3 or -O3 are specified on the
     compiler command line.  A vector version of the single-precision and
     double-precision LOG intrinsic exists on IRIX systems and is used when
     -O3 is specified on the compiler command line.

     These functions evaluate y = ln(x).

     CDLOG is called implicitly by as a result of a generic ALOG call with
     a complex double-precision argument.

NOTES
     The ALOG, DLOG, and CLOG intrinsic function names can be passed as
     arguments; the others cannot.

     On CRAY T90 systems that support IEEE arithmetic, the following return
     values occur:

          ALOG(0) = -infinity

          ALOG(-0) = NaN

          ALOG(x) = NaN if -infinity <= x < 0

          ALOG(infinity) = infinity

RETURN VALUES
     The generic function LOG becomes a call to one of the other functions
     depending on the type of its argument.

     ALOG returns the real natural logarithm of its real argument.

     DLOG returns the double-precision natural logarithm of its
     double-precision argument.

     QLOG returns the quad-precision natural logarithm of its
     quad-precision argument.

     CLOG returns the complex natural logarithm of its complex argument.
     Its argument cannot equal (0.,0.).  The range of the imaginary part is
     -pi < imaginary_part <= pi.

     CDLOG returns the complex double-precision natural logarithm of its
     complex double-precision argument.

     CQLOG returns the complex quad-precision natural logarithm of its
     complex quad-precision argument.

     The data type and kind type for real, double-precision, and
     quad-precision values differ depending on your platform.  For
     platform-specific information, see the TERMINOLOGY section of the
     INTRO_INTRIN(3I) man page.

SEE ALSO
     Intrinsic Procedures Reference Manual for the printed version of this
     man page.