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591
Floating-point Math Instructions
Section 3-15
Real number = (–1)
s
2
e–127
(1.f)
s: Sign
e: Exponent
f: Mantissa
The floating-point data format conforms to the IEEE754 standards. Data is
expressed in 32 bits, as follows:
Number of Digits
The number of effective digits for floating-point data is seven digits for deci-
mal.
Floating-point Data
The following data can be expressed by floating-point data:
• –
∞
• –3.402823 x 10
38
≤
value
≤
–1.402398 x 10
–45
• 0
• 1.402398 x 10
–45
≤
value
≤
3.402823 x 10
38
• +
∞
• Not a number (NaN)
Special Numbers
The formats for NaN,
±∞
, and 0 are as follows:
NaN*:
e = 255, f
≠
0
+
∞
:
e = 255, f = 0, s= 0
–
∞
:
e = 255, f = 0, s= 1
0:
e = 0
*NaN (not a number) is not a valid floating-point number. Executing floating-
point calculation instructions will not result in NaN.
Writing Floating-point
Data
When floating-point is specified for the data format in the I/O memory edit dis-
play in the CX-Programmer, standard decimal numbers input in the display
are automatically converted to the floating-point format shown above
(IEEE754-format) and written to I/O Memory. Data written in the IEEE754-for-
mat is automatically converted to standard decimal format when monitored on
the display.
Data
No. of bits
Contents
s: sign
1
0: positive; 1: negative
e: exponent
8
The exponent (e) value ranges from 0 to 255.
The actual exponent is the value remaining after
127 is subtracted from e, resulting in a range of
–127 to 128. “e=0” and “e=255” express special
numbers.
f: mantissa
23
The mantissa portion of binary floating-point
data fits the formal 2.0 > 1.f
≥
1.0.
s
e
f
31 30
23 22
0
Sign
Exponent
Mantissa
−
1.402398 x 10
–45
1.402398 x 10
–45
–
∞
+
–3.402823 x 10
38
3.402823 x 10
38
–1
0
1
∞
Содержание SYSMAC CS1D-CPU**
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Страница 185: ...146 List of Instructions by Function Code Section 2 4...
Страница 193: ...154 3 35 4 MOVE BIT MOVBC 568 1274 3 35 5 BIT COUNTER BCNTC 621 1276 3 35 6 GET VARIABLE ID GETID 286 1278...
Страница 1389: ...1350 CJ series Instruction Execution Times and Number of Steps Section 4 2...
Страница 1390: ...1351 Appendix A ASCII Code Table ASCII SP Four leftmost bits Four rightmost bits...
Страница 1391: ...1352 ASCII Code Table Appendix A...