XQuery

xs:float

The primitive type xs:float is patterned after an IEEE single-precision 32-bit floating-point number. The lexical representation is a mantissa (a decimal number) followed, optionally, by the letter E (in upper- or lowercase), followed by an integer exponent. For example, 3E2 represents 3 × 10², or 300. In addition, there are three special values: INF, (infinity), -INF (negative infinity), and NaN (not a number).

Table B-10 lists some values of the xs:float type.

Table B-10. Values of the xs:float type

Values	Explanation
Valid
-5E12
44.56E5
+23.2e−2
12
+3.5	Any value valid for xs:decimal is also valid for xs:float and xs:double
−0	Negative zero
INF	Positive infinity
NaN	Not a number
Invalid
−5E3.5	The exponent must be an integer
37E	An exponent must be specified if E is present
	An empty value or zero-length string is not permitted

XQuery makes a distinction between positive and negative zero values for the xs:float type. 0 and −0 are considered to be equal but separate values.

The implementation has some flexibility regarding how to handle overflow or underflow occurs during arithmetic operations on xs:float values. The processor may raise an error. Alternatively, in an overflow situation, it may return INF, -INF, or the largest or smallest possible value. For underflow, it may return the closest possible value to zero.

Casting xs:float Values

Values of type xs:float can be cast to and from any of the other numeric types. Casting among numeric ...