FEXP

Function (Macro constructor)

A deprecated macro used to define floating point numbers.

Yet one deprecated macro. FEXP(m,e) constructs a number m*10^e where m is a sequence of digits (without decimal point) which is assumed to represent decimal number m.mmmm..., e.g. FEXP(2514,5) represents number 2.514*10^5 (251400 or 2.514e5 using conventional exponential notation), and FEXP(42,-3) represents number 4.2*10^-3 (0.0042 or 4.2e-3). FEXP(1,3) is 1*10^3 (1000 or 1e3). mantissa must be the constant sequence of digits, without leading zeros, but the way on which FEXP is implemented allows that exponent may be a variable or an expression, like FEXP(314,a), when even mantissa is not a constant, you can use function ldexp10. Anyway, you don't need to use FEXP any more: simply use conventional exponential notation. E.g. simply use 4.2e3 instead of FEXP(42,3) etc.

Note that a = FEXP(m,e) is not the same as bcd_var(a).exponent = e+0x4000 and bcd_var(a).mantissa = m. The first part is true; the second is not. More precise, FEXP shifts m to the left enough number of times to produce correct normalized mantissa (see bcd for more info). So, when you type a = FEXP(352,3) it works like bcd_var(a).exponent = 0x4003 and bcd_var(a).mantissa = 0x3520000000000000. For more description about internal format of floating point numbers, see bcd.