HP 3000 Manuals

Compiler Library/XL Reference Manual

DLOG (or DLOG') or DLOG10 

DLOG calculates the natural logarithm of a positive longreal number;
DLOG10 calculates the base 10 logarithm of a positive longreal number.

Declaration 

FUNCTION DLOG(VAR x:LONGREAL):LONGREAL; EXTERNAL;
                or
 FUNCTION DLOG10(VAR x:LONGREAL):LONGREAL; EXTERNAL;

Accuracy 

	       Click here to view figure.
Attributes 

Parameter:                A representable positive longreal number.  See
                          Chapter 1 for details on the internal
                          representation of longreal numbers.

Result:                   A longreal number (DLOG10 = DLOG * log10 (e)).

HP FORTRAN 77/XL:         Intrinsic function:  Y=DLOG(X) or Y=DLOG10(X).

Error:                    If the argument is a NaN or a negative number,
                          there are two possible actions.  If the INVALID
                          trap is enabled, the message "DLOG(X): X< 0.0
                          OR X=NaN" or "DLOG10(X): X <0.0 OR X=NaN"
                          occurs.  Otherwise, the INVALID flag is set.
                          In either case, a quiet NaN is returned.

Special Values 

                          dlog (+Infinity) = +Infinity

                          dlog (0) = -Infinity

MPE/iX 5.0 Documentation