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LOG(P)
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7.12 Special function instructions
7.12.23 Natural logarithm operation on floating-point data (Single precision) (LOG(P))
Operation Error
(1) In any of the following cases, an operation error occurs, the error flag (SM0) turns ON, and
an error code is stored into SD0.
• The value designated by is negative. (Error code: 4100)
• The value designated by is 0. (Error code: 4100)
• The contents of the designated device or the result of the addition are not "0", or not within
the following range(For the Universal model QCPU only): (Error code: 4140)
0, 2
-126
| Contents of designated device | < 2
128
• The value of the specified device is 0. *
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(For the Basic model QCPU, High Performance model QCPU, Process CPU, Redundant
CPU) (Error code: 4100)
*3: There are CPU modules that will not result in an operation error if 0 is specified. For details, refer to 3.2.4.
• The result exceeds the following range (Operation results in an overflow)
(For the Universal model QCPU only)
2
128
| Operation result | (Error code: 4141)
• The value of the specified device is 0, unnormalized number, nonnumeric, and ± .
(For the Universal model QCPU only) (Error code: 4140)
Program Example
(1) The following program seeks the natural logarithm of the value "10" set by D50, and stores
the result at D30 and D31.
[Ladder Mode]
[List Mode]
[Operation]
S
S
Sets data used for natural
logarithm operation ( )
Converts the operation data
into a 32-bit floating-point real number ( )
Executes natural logarithm operation ( )
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Step Instruction Device
D50
10
MOV
b15 b0
BIN value
10
Conversion to
floating-point
FLT
LOG operation
D41
D40
LOG
D31
D30
32-bit floating-point
real number
32-bit floating-point
real number
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02
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302585
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