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4.1.1
Exponential/Logarithmic Functions
When an exponential or logarithmic function receives power flow, it performs the appropriate
operation on the REAL or LREAL input value(s) and places the result in output Q.
The inverse natural log (EXP)
function raises e to the power
specified by IN.
The Power of X (EXPT) function
raises the value of input IN1 to
the power specified by the value
IN2.
The Base 10 Logarithm (LOG)
function calculates the base 10
logarithm of IN.
The Natural Logarithm (LN)
function calculates the logarithm
of IN.
The power flow output is energized when the function is performed, unless Overflow or one of the
following invalid conditions occurs:
IN < 0, for LOG or LN
■
IN1 < 0, for EXPT
■
IN is negative infinity, for EXP
■
IN, IN1, or IN2 is a NaN (Not a Number)
■
Operands of the Exponential/Logarithmic Functions
Parameter
Description
IN or IN1
For EXP, LOG, and LN, IN contains the REAL or LREAL value
to be operated on.
The EXPT function has two inputs, IN1 and IN2. For EXPT,
IN1 is the base value and IN2 is the exponent.
IN2 (EXPT)
The REAL or LREAL exponent for EXPT.
Q
Contains the REAL or LREAL logarithmic/exponential value
of IN or of IN1 and IN2.
GFK-2950C
Chapter 4. Ladder Diagram (LD) Programming
February 2018
Allowed Operands
All except variables
located in %S—%SC
All except variables
located in %S—%SC
All except constants and
variables located in
%S—%SC
Optional
No
No
No
63
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