16. CUSTOM MACRO
Brackets ([, ]) are used to enclose an expression. Note that parentheses
are used for comments.
Errors may occur when operations are performed.
Table 16.3 (b) Errors involved in operations
Type of error
a = b*c 1.55×10
a = b / c 4.66×10
a = b + c
a = b – c
a = SIN [ b ]
a = COS [ b ]
a = ATAN [ b ] / [ c ]
1 The relative error depends on the result of the operation.
2 Smaller of the two types of errors is used.
3 The absolute error is constant, regardless of the result of the
4 Function TAN performs SIN/COS.
5 If the result of the operation by the SIN, COS, or TAN
function is less than 1.0 x 10
or is not 0 because of the
precision of the operation, the result of the operation can be
normalized to 0 by setting bit 1 of parameter No. 6004 to 1.
S The precision of variable values is about 8 decimal digits. When very
large numbers are handled in an addition or subtraction, the expected
results may not be obtained.
When an attempt is made to assign the following values to variables
#1 and #2:
the values of the variables become:
In this case, when #3=#2–#1; is calculated, #3=100000.000 results.
(The actual result of this calculation is slightly different because it is
performed in binary.)
S Also be aware of errors that can result from conditional expressions
using EQ, NE, GE, GT, LE, and LT.
D Operation error
a + b