I'd say the answer depends on the rounding mode when converting the double
to float
. float
has 24 binary bits of precision, and double
has 53. In binary, 0.1 is:
0.1₁₀ = 0.0001100110011001100110011001100110011001100110011…₂
^ ^ ^ ^
1 10 20 24
So if we round up at the 24th digit, we'll get
0.1₁₀ ~ 0.000110011001100110011001101
which is greater than the exact value and the more precise approximation at 53 digits.