&gt; If it&#x27;s fixed-precision it&#x27;s not floating point<p>I&#x27;m not referring to fixed point, but fixed-size representation.<p>&gt; If you didn&#x27;t mean fixed-precision, then I&#x27;m not sure how actual floating points could sanely act as a hash key.<p>I don&#x27;t see what the problem is. Certainly, there&#x27;s problems if you do certain floating point calculations and blindly look for the result as a key in a mapping, but that&#x27;s not a problem with floats as keys, its a problem with that particular usage pattern.