Propeller Manual

CON – Spin Language Reference
Page 86 · Propeller Manual v1.1
value is a floating-point value; the expression must either be a single floating-point value or
be made up entirely of floating-point values (no integers).
Floating-point values must be written as:
1) decimal digits followed by a decimal point and at least one more decimal digit,
2) decimal digits followed by “e” (for exponent) and an integer exponent value, or,
3) a combination of 1 and 2.
The following are examples of valid constants:
0.5 floating-point value
1.0 floating-point value
3.14 floating-point value
1e16 floating-point value
51.025e5 floating-point value
3 + 4 integer expression
3.0 + 4.0 floating-point expression
3.0 + 4 invalid expression; causes compile error
3.0 + FLOAT(4) floating-point expression
Here is an example declaring an integer constant and two floating-point constants.
CON
Num1 = 20
Num2 = 127.38
Num3 = 32.05 * 18.1 - Num2 / float(Num1)
The above code sets Num1, Num2 and Num3 to 20, 127.38 and 573.736, respectively. Notice that
the last expression required
Num1 to be enclosed in the FLOAT declaration so that the compiler
treats it as a floating-point value.
T
The Propeller compiler handles floating-point constants as a single-precision real number as
described by the IEEE-754 standard. Single-precision real numbers are stored in 32 bits, with
a 1-bit sign, an 8-bit exponent, and a 23-bit mantissa (the fractional part). This provides
approximately 7.2 significant decimal digits.