Campbell Scientific CR9000X Measurement and Control System - Manual (Page 76)

Section 2. Data Storage and Retrieval
2.2.1.2 Floating Point Math, NAN, and ±INF
Table 2.2-1 lists math expressions, their CRBASIC form, and IEEE
floating point math result loaded into variables declared as FLOAT or
STRING.
TABLE 2.2-1. Math Expressions and CRBASIC Results
Expression CRBASIC Expression Result
0 / 0 0 / 0 NAN
∞ - ∞ (1 / 0) - (1 / 0) NAN
(-1)
∞ -1 ^ (1 / 0) NAN
0 * (
- ∞ )
0 * (-1 * (1 / 0)) NAN
± ∞ /± ∞ (1 / 0) / (1 / 0) NAN
1
∞ 1 ^ (1 / 0) NAN
0 * ∞ 0 * (1 / 0) NAN
x / 0 1 / 0 INF
x / -0 1 / -0 INF
-x / 0 -1 / 0 -INF
-x / -0 -1 / -0 -INF
∞ 0 (1 / 0) ^ 0 INF
0
∞ 0 ^ (1 / 0) 0
0 0 0 ^ 0 1
NAN and ±INF are presented differently depending on the declared
variable data type. Further, they are recorded differently depending on the
final storage data type chosen compounded with the declared variable data
type used as the source.
For example, INF in a variable declared as LONG is represented by the
integer -2147483648. When that variable is used as the source, the final
storage word when sampled as UINT2 is stored as 0. See Table 2.2-2
below.
TABLE 2.2-2. Variable and Final Storage Data Types with NAN and ±INF
Variable Test Variable's Final Storage Data Type & associated stored value
Type Expression Value FP2 IEEE4 UINT2 STRING BOOL LONG
1 / 0 INF INF INF 65535 +INF TRUE 2,147,483,647
As FLOAT
0 / 0 NAN NAN NAN 0 NAN TRUE -2,147,483,648
1 / 0 2,147,483,647 7999 2.147484E+09 65535 2147483647 TRUE 2,147,483,647
As LONG
0 / 0 -2,147,483,648 -7999 -2.147484E+09 0 -2147483648 TRUE -2,147,483,648
1 / 0 TRUE -1 -1 65535 -1 TRUE -1 As
BOOLEAN 0 / 0 TRUE -1 -1 65535 -1 TRUE -1
1 / 0 +INF INF INF 65535 +INF TRUE 2,147,483,647
As STRING
0 / 0 NAN NAN NAN 0 NAN TRUE -2,147,483,648
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