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Floating-point Math Instructions
5-21-19 LOGARITHM: LOG(468)
Ladder Symbol
(468)
LOG
S
Variations
↑LOG(468)
Description
Relation Between Input Data and Result
Precautions
Flags
300
Operand Data Areas
S: First source word
R
R: First result word
When the execution condition OFF, LOG(468) is not executed. When the execu-
tion condition is ON, LOG(468) computes the natural logarithm for the 32-float-
ing-point content of S and S+1, and places the result in R and R+1. The opera-
tion is executed with 2.718282 taken as the base (e).
log
S+1
e
R+1
If the absolute value of the result is greater than the maximum value that can be
expressed for floating-point data, the Overflow Flag (A50009) will turn ON and
the result will be output as ±R.
S and S+1must be non-negative floating-point data.
Note Refer to page 101 for general precautions on operand data areas.
ER (A50003):
S and S+1is a negative number.
S and S+1is not floating-point data.
The content of a*DM word is not BCD when set for BCD.
EQ (A50006):
The exponent and mantissa of the result are 0.
N (A50008):
The result is a negative number.
OF (A50009):
The absolute value of the result is greater than the maximum
value that can be expressed for floating-point data.
UF (A50010):
OFF when the computation is executed.
CIO, G, A, T, C, #, DM
CIO, G, A, DM
Source (floating-point data, 32 bits)
S
Result (exponent, floating-point data,
R
32 bits)
R
S: Input data
R: Result
Section 5-21
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