Context: https://stackoverflow.com/a/39707410/1778275 :
If the floating point type used a base 10 presentation, LDBL_DIG and LDBL_DECIMAL_DIG would have the same value.
Question: why base-2 leads to FLT_DIG != FLT_DECIMAL_DIG?
The same question goes for prefixes: DBL_, LDBL_, FLT16_.
