Mitsubishi Q00JCPU User Manual page 931

APPENDICES
(3) Advantages and disadvantages when using the double-precision
TableApp.74 Comparison between single-precision and double precision floating-point data
Item
Word point required for data retention
Setting range
Mantissa part
Precision (number of bits) Exponent part
Sign part
Data comparison
(Conductive status)(LDE>= /
LDED>=)
Instruction processing
Data transfer(EMOV/
speed (Q04UDHCPU/
EDMOV)
Q06UDHCPU)(Maximum)
Addition (3 devices)(E+ /
ED+)
SIN operation(SIN/SIND)
Appendix 5 Method of replacing High Performance model QCPU with Universal model QCPU
floating-point data of the Universal model QCPU
TableApp.73 shows the advantages and disadvantages when performing the double-
precision floating-point operation instructions in the Universal model QCPU.
If higher accuracy is required in floating-point operations, it is recommended to
replace the instructions with the double-precision floating-point operation instructions.
TableApp.73 Advantages and disadvantages when using the double-precision floating-point
Advantage
The results are more accurate than those
of the single-precision floating-point
operation instructions.
* 1: The processing speed of the double-precision floating-point operation instructions in the Universal
model QCPU is higher than that of floating-point operation instructions using internal double-
precision operations in the High Performance model QCPU.
TableApp.74 shows the comparison between single-precision and double precision
floating-point data.
Single-precision floating-point data Double-precision floating-point data
operation instructions
The instruction processing speed is slower than that of the
single-precision floating-point operation instructions. *1
Double-precision floating-operation data use twice as many
word device points as single-precision floating-operation
data.
2 words
128 -126
-2 <N -2 , 0,
-126 128
2 N<2
23
bits
8
bits
1
bits
5.5
µs
0.019
µs
0.0665
µs
5.7
µs
Disadvantage
4 words
1024 -1022
-2 <N -2 , 0,
-1022 1024
2 N<2
52
bits
11
bits
1
bits
9.0
µs
5.0
µs
9.2
µs
13.8
µs
App
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10
11
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