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GFK-0467K Chapter 4 Series 90-30/20/Micro Instructions Set 4-37
4
Logarithmic/Exponential Functions (LOG, LN, EXP, EXPT)
The LOG, LN, and EXP functions have two input parameters and two output parameters. When the
function receives power flow, it performs the appropriate logarithmic/exponential operation on the
real value in input IN and places the result in output Q.
• For the LOG function, the base 10 logarithm of IN is placed in Q.
• For the LN function, the natural logarithm of IN is placed in Q.
• For the EXP function, e is raised to the power specified by IN and the result is placed in Q.
• For the EXPT function, the value of input I1 is raised to the power specified by the value I2
and the result is placed in output Q. (The EXPT function has three input parameters and two
output parameters.)
The ok output will receive power flow, unless IN is NaN (Not a Number) or is negative.
_____
| |
(enable) —| LOG_|— (ok)
| |
| REAL|
| |
| |
(input parameter IN) —|IN Q|— (output parameter Q)
|_____|
Parameters:
Parameter Description
enable When the function is enabled, the operation is performed.
IN IN contains the real value to be operated on.
ok The ok output is energized when the function is performed without overflow,
unless an invalid operation occurs and/or IN is NaN or is negative.
Q Output Q contains the logarithmic/exponential value of IN.
Note
The LOG, LN, EXP and EXPT functions are only available on the 350 and 360
series CPUs, Release 9 or later, or on all releases of CPU352.