Peter Otten wrote:
Move it into a function; this turns a and i into local variables.
def f():
imax = 1000000000
a = 0
for i in xrange(imax):
a = a + 10
print a
f()
Wow. It is still slower than Matlab, but your suggestion speeds up the
code by ca 50%.
But I do not understand why the change of a global to a local variable
gives such a big difference.
$ cat addition.py
imax = 1000000000
a = 0
for i in xrange(imax):
a = a + 10
print a
$ cat additionOtten.py
def f():
imax = 1000000000
a = 0
for i in xrange(imax):
a = a + 10
print a
f()
$ /usr/bin/time --verbose python addition.py
10000000000
Command being timed: "python addition.py"
User time (seconds): 110.52
System time (seconds): 0.01
Percent of CPU this job got: 98%
Elapsed (wall clock) time (h:mm:ss or m:ss): 1:52.76
[...]
$ /usr/bin/time --verbose python additionOtten.py
10000000000
Command being timed: "python additionOtten.py"
User time (seconds): 56.38
System time (seconds): 0.00
Percent of CPU this job got: 99%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:56.64
[...]
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