Compiler Library/XL Reference Manual (32650-90029)

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to 1 if the matrix is non-singular or 0 if the

matrix is singular and no inverse exists.

HP FORTRAN 77/XL: Callable as a system intrinsic:

CALL DINVERT(n, a, d)

Error: None.

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;

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 (

)).

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

DMOD

DMOD calculates a longreal number modulus a second longreal number.

Declaration

FUNCTION DMOD(VAR x,y:LONGREAL):LONGREAL; EXTERNAL;

Attributes

Parameters: Both arguments are longreal numbers.

Result: A longreal number.

When x-y ~ ∈ , maximum f-g ~ ∈

1n(x)