Python: Zero

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Nothing is something!

The value zero is the identity element for addition.

What is the identity element for multiplication?

The IEEE (Institute of Electrical and Electronic Engineers) standard for floating point operations defines the following values.

+0.0
-0.0

The values positive zero and negative zero compare as equal, but have different representations.

Here is the Python code [#1]

import math
print("Zeros:")
print("")
e0 = 0.0
print("{0:5.2f} (no sign)".format(e0))
e1 = +0.0
print("{0:5.2f} (positive)".format(e1))
e2 = -0.0
print("{0:5.2f} (negative)".format(e2))
print("")
if e1 == e2:
	print("{0:0.2f} equals {1:0.2f}".format(e1,e2))
else:
	print("{0:0.2f} does not equal {1:0.2f}".format(e1,e2))
e3 = abs(e2)
print("abs({0:0.2f}) is {1:5.2f}".format(e2,e3))
print("")
sign1 = math.copysign(1.0,e1)
sign2 = math.copysign(1.0,e2)
print("Sign of {0:0.1f} is {1:0.1f}".format(e1,sign1))
print("Sign of {0:0.1f} is {1:0.1f}".format(e2,sign2))

Here is the output of the Python code.

Zeros:
 0.00 (no sign)
 0.00 (positive)
-0.00 (negative)
0.00 equals -0.00
abs(-0.00) is  0.00
Sign of 0.0 is 1.0
Sign of -0.0 is -1.0

Note: The math.copysign returns the first argument (which should be positive) with the sign of the second argument. This provides a way to find out of a zero is a positive or a negative zero