Re: [boost] Proposed: a new sequence adapter for MPL (product_view)

From: Max Motovilov (max_at_[hidden])
Date: 2008-03-12 21:21:15

Some final comments.

First, in the code I posted above "push_back< S, A>" should be replaced 
with "push_front< S, A >", otherwise top-level sequence cannot be a list.

Second, while recursive implementation is very similar to the iterative, 
it still generates the combinations in reverse order :)  Not important 
for applications I can think of, but still.

Finally, the performance comparison. I did it with GCC 4.2 on an Intel 
dual core with 4G RAM running 64-bit Ubuntu Gutsy.

Iterative algorithm:

2^1 combinations: real	0m0.491s, user	0m0.432s, sys	0m0.048s
2^2 combinations: real	0m0.589s, user	0m0.488s, sys	0m0.084s
2^3 combinations: real	0m0.973s, user	0m0.624s, sys	0m0.060s
2^4 combinations: real	0m1.078s, user	0m0.824s, sys	0m0.120s
2^5 combinations: real	0m1.542s, user	0m1.424s, sys	0m0.092s
2^6 combinations: real	0m3.384s, user	0m3.012s, sys	0m0.212s
2^7 combinations: real	0m10.627s, user	0m8.781s, sys	0m0.320s
2^8 combinations: real	0m35.032s, user	0m33.582s, sys	0m0.652s
2^9 combinations: hit compiler limits, graceful exit

Recursive algorithm:

2^1 combinations: real	0m0.493s, user	0m0.420s, sys	0m0.072s
2^2 combinations: real	0m0.584s, user	0m0.480s, sys	0m0.100s
2^3 combinations: real	0m0.934s, user	0m0.716s, sys	0m0.076s
2^4 combinations: real	0m1.795s, user	0m1.408s, sys	0m0.088s
2^5 combinations: real	0m5.507s, user	0m4.740s, sys	0m0.192s
2^6 combinations: real	0m29.325s, user	0m27.294s, sys	0m0.584s
2^7 combinations: overwhelmed system resources after 5min, killed