DBLB real-valued function
Syntax
DBLB ($string, first_char)
Function
Return the value of eight bytes of a string interpreted as an IEEE double-precision floating-point number.
Parameters
|
$string |
String expression that contains the eight bytes to be converted. |
|
first_char |
Optional real-valued expression that specifies the position of the first of the eight bytes in the string. If first_char is omitted or has a value of 0 or 1, the first eight bytes of the string are extracted. If first_char is greater than 1, it is interpreted as the character position for the first byte. For example, a value of 2 means that the second through ninth bytes are extracted. If first_char specifies eight bytes that are beyond the end of the input string, an error is generated . |
Details
Eight sequential bytes of the given string
are interpreted as being a double-precision (64-bit) floating-point number in
the IEEE standard format. This 64-bit field is interpreted as follows:
where
s is the sign bit, s = 0 for positive, s = 1 for negative.
exp is the binary exponent, biased by -1023.
fraction is a binary fraction with an implied 1 to the left of the binary point.
For 0 < exp < 2047, the value of a floating point number is:
-1s * (1.fraction) * 2exp-1023
Double-precision real values have the following special values:
| exp | fraction | Description |
|---|---|---|
| 0 | Zero | Zero value |
| 0 | Nonzero | Denormalized number |
| 2047 | Zero | Signed infinity |
| 2047 | Nonzero | Not-a-number |
The range for normalized numbers is approximately 2.2 x 10-308 to 1.8 x 10307
The main use of this function is to convert a binary floating-point number from an input data record to a value that can be used internally by V+.
Example
DBLB($CHR(^H3F)+$CHR(^HF0)+$CHR(0)+$CHR(0) +$CHR(0)+$CHR(0)+$CHR(0)+$CHR(0)) ;Returns 1.0
Related Keywords
ASC real-valued function
$DBLB string function
DOUBLE (type keyword for AUTO, GLOBAL, and LOCAL)
FLTB real-valued function
$FLTB string function
INTB real-valued function
TRANSB transformation function
VAL real-valued function
