A HiLog floating-point number consists of a sequence of digits with an
embedded decimal point, optionally preceded by a minus sign ( '-'), and
optionally followed by an exponent consisting of uppercase or lowercase
'E' and a signed base integer.
Using these rules, examples of HiLog floating point numbers are:
1.0 -34.56 817.3E12 -0.0314e26 2.0E-1
Note that in any case there must be at least one digit before, and one digit
after, the decimal point.