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9.177 LOG — Natural logarithm function ¶

Description:

LOG(X) computes the natural logarithm of X, i.e. the logarithm to the base e.

Standard:

Fortran 77 and later, has GNU extensions

Class:

Elemental function

Syntax:

RESULT = LOG(X)

Arguments:

X	The type shall be REAL or COMPLEX.

Return value:

The return value is of type REAL or COMPLEX. The kind type parameter is the same as X. If X is COMPLEX, the imaginary part \omega is in the range -\pi < \omega \leq \pi.

Example:

program test_log
  real(8) :: x = 2.7182818284590451_8
  complex :: z = (1.0, 2.0)
  x = log(x)    ! will yield (approximately) 1
  z = log(z)
end program test_log

Specific names:

Name	Argument	Return type	Standard
ALOG(X)	REAL(4) X	REAL(4)	Fortran 77 or later
DLOG(X)	REAL(8) X	REAL(8)	Fortran 77 or later
CLOG(X)	COMPLEX(4) X	COMPLEX(4)	Fortran 77 or later
ZLOG(X)	COMPLEX(8) X	COMPLEX(8)	GNU extension
CDLOG(X)	COMPLEX(8) X	COMPLEX(8)	GNU extension