python's negative threshold, the lowest non-infinity negative number?
Question: What is python's threshold of representable negative numbers? What's the
lowest number below which Python will call any other value a - negative
inifinity?


Answer: There is no most negative integer, as Python integers have arbitrary
precision. The smallest float greater than negative infinity (which, depending
on your implementation, can be represented as `-float('inf')` can be found in
`sys.float_info`.

    
    
    >>> import sys
    >>> sys.float_info.max
    1.7976931348623157e+308
    

The actual values depend on the actual implementation, but typically uses your
C library's `double` type. Since floating-point values typically use a sign
bit, the smallest negative value is simply the inverse of the largest positive
value. Also, because of how floating point values are stored (separate
mantissa and exponent), you can't simply subtract a small value from the
"minimum" value and get back negative infinity. Subtracting 1, for example,
simply returns the same value due to limited precision.

(In other words, the possible `float` values are a small subset of the actual
real numbers, and operations on two `float` values is not necessarily
equivalent to the same operation on the "equivalent" reals.)

