

In [1]:

    
%load_ext cython

Demonstration of integer overflow



In [4]:

    
%%cython
# cython: language_level=3

# int would overflow, but unsigned int won't
cpdef f():
    cdef int i  # Max value: 2147483647
    for i in range(2147483645, 2147483650):
        print(i)



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f()









    



2147483645
2147483646
2147483647
-2147483648
-2147483647



In [6]:

    
%%cython
# cython: language_level=3

# int would overflow, but unsigned int won't
cpdef f():
    cdef unsigned int i  # Max value: 2147483647
    for i in range(2147483645, 2147483650):
        print(i)



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f()

Demonstration of floating-point error

1) Loss of precision



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%%cython
# cython: language_level=3

# float would lose precision, but double won't
cpdef g():
    cdef float x, y, z
    x = 1
    y = 1e-15
    z = x + y
    print('x =     ', x)
    print('y =     ', y)
    print('x + y = ', z)



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g()









    



x =      1.0
y =      1.0000000036274937e-15
x + y =  1.0



In [10]:

    
%%cython
# cython: language_level=3

# float would lose precision, but double won't
cpdef g():
    cdef double x, y, z
    x = 1
    y = 1e-15
    z = x + y
    print('x =     ', x)
    print('y =     ', y)
    print('x + y = ', z)



In [11]:

    
g()









    



x =      1.0
y =      1e-15
x + y =  1.000000000000001

2) Misrepresentation



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%%cython
# cython: language_level=3

cpdef h():
    cdef float x = 0.1
    print('x =     ', x)



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h()









    



x =      0.10000000149011612



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%%cython
# cython: language_level=3

cpdef h():
    cdef double x = 0.1
    print('x =     ', x)



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h()









    



x =      0.1



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