Reference Guide

3-6 Full Command and Function Reference
ACK has no effect on control alarms. Control alarms that come due are automatically
acknowledged and saved in the system alarm list.
Access: …Ó TOOLS ALRM ACK (Ó is the right-shift of the 9 key).
Flags: Repeat Alarms Not Rescheduled (–43), Acknowledged Alarms Saved (–44)
Input/Output: None
See also: ACKALL
ACKALL
Type: Command
Description: Acknowledge All Alarms Command: Acknowledges all past-due alarms.
ACKALL clears the alert annunciator if there are no other active alert sources (such as a low
battery condition).
ACKALL has no effect on control alarms. Control alarms that come due are automatically
acknowledged and saved in the system alarm list.
Access: …Ó TOOLS ALRM ACKALL ( Ó is the right-shift of the 9 key).
Flags: Repeat Alarms Not Rescheduled (–43), Acknowledged Alarms Saved (–44)
Input/Output: None
See also: ACK
ACOS
Type: Analytic Function
Description: Arc Cosine Analytic Function: Returns the value of the angle having the given cosine.
For a real argument x in the domain –1 ≤x ≤ 1, the result ranges from 0 to 180 degrees (0 to π
radians; 0 to 200 grads).
A real argument outside of this domain is converted to a complex argument, z = x + 0i, and the
result is complex.
The inverse of COS is a relation, not a function, since COS sends more than one argument to the
same result. The inverse relation for COS is expressed by ISOL as the general solution
s1*ACOS(Z)+2*π*n1
The function ACOS is the inverse of a part of COS, a part defined by restricting the domain of
COS such that:
• each argument is sent to a distinct result, and
• each possible result is achieved.
The points in this restricted domain of COS are called the principal values of the inverse relation.
ACOS in its entirety is called the principal branch of the inverse relation, and the points sent by
ACOS to the boundary of the restricted domain of COS form the branch cuts of ACOS.
The principal branch used by the calculator for ACOS was chosen because it is analytic in the
regions where the arguments of the real-valued inverse function are defined. The branch cut for the
complex-valued arc cosine function occurs where the corresponding real-valued function is
undefined. The principal branch also preserves most of the important symmetries.
The graphs below show the domain and range of ACOS. The graph of the domain shows where
the branch cuts occur: the heavy solid line marks one side of a cut, while the feathered lines mark
the other side of a cut. The graph of the range shows where each side of each cut is mapped
under the function.
These graphs show the inverse relation s1*ACOS(Z)+2*π*n1 for the case s1=1 and n1 = 0. For
other values of s1 and n1, the vertical band in the lower graph is translated to the right or to the
left. Taken together, the bands cover the whole complex plane, which is the domain of COS.