I wrote the following correct but inefficient test of primality for purposes
of demonstrating that the simplest algorithm is often not the most
efficient. But, when I try to run the following code with a value of n that
is large enough to produce a significant amount of running time, I get an
out-of-memory error!
def is_prime(n):
for j in range(2,n):
if (n % j) == 0: return False
return True
It seems as though Python is actually expanding range(2,n) into a list of
numbers, even though this is incredibly wasteful of memory. There should be
a looping mechanism that generates the index variable values incrementally
as they are needed.
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