DLOG (or DLOG') or DLOG10 [ Compiler Library/XL Reference Manual ] MPE/iX 5.0 Documentation
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
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