Mitsubishi Electric MELSEC-Q/L - Natural Logarithm Operation on Floating-Point Data (Double Precision)

640
7 APPLICATION INSTRUCTIONS
7.12 Special Function Instructions
Natural logarithm operation on floating-point data (double
precision)
LOGD(P)
Processing details
• Returns the natural logarithm of the value designated by (S) taking (e) as base, and stores operation results at device
designated by (D).
• Only positive values can be designated by (S). (Operation cannot be performed on negative numbers.)
• When the operation results in -0 or an underflow, the result is processed as 0.
• When an input value is set using a programming tool, a rounding error may occur. For precautions, refer to Page 89
Precautions.
Operation error
• In any of the following cases, an operation error occurs, the error flag (SM0) turns ON, and an error code is stored into SD0.
(S): Data of which the natural logarithm is obtained or head number of the devices where the data is stored (real number)
(D): Head number of the devices where the operation result will be stored (real number)
Setting
data
Internal device R, ZR J\ U\G Zn Constant
E
Others
Bit Word Bit Word
(S)   
(D)   
Error
code
Error details Q00J/
Q00/
Q01
QnH QnPH QnPRH QnU LCPU
4100 The value specified in (S) is negative.
The value specified in (S) is 0.

4140 The specified device value is not within the following range:
0, 2
-1022
 | Specified device value | <2
1024
The value of the specified device is -0, a subnormal number, NaN (not a
number), or .

4141 The operation result exceeds the following range.
(when an overflow occurs)
|Operation result| < 2
1024

Universal LCPU
Basic
High
performance
Process Redundant
Command
Command
LOGDP
LOGD
LOGDP
LOGD
S
D
S D
log
(
)( )
64-bit floating-point
real number
64-bit floating-point
real number
+3
S
+2
S
S
+1
S
+3
D
+2
D
D
+1
D