Performance test for isPrimeSearch

whl – used a while loop to loop over all the numbers in the interval
wsa – used a while loop to loop over all the numbers in the interval, but added a skip-ahead if a prime is found, since no two primes bigger than 3 is next to each other
for – used a for loop to loop over all the numbers in the interval

Note that CheckForPrime6 is the best algorithm, however, there is not really a better solution for whl, wsa or for. More testing is needed.

While each table represents a unique test done on one machine, each table can be done on different machines. The internal relative position/result of the test within a table can, therefore, be used, but an overall comparison of the times can not.

Lowest number per table is marked with *. Note that not all tests have been performed with all algorithms. This has been dependent on what has been under investigation.

Results have shown that an ordinary while loop is almost never faster than wsa or for. The results where it was the fastest have been rerun, and the CheckPrime6 was the slowest with the while loop. Original results kept on the page but must be due to some fluke on the test machine.
*

Searching from 200 to 400 (interval: 200)

Function	While	While skip ahead	For
CheckForPrime1	0.0011	0.0006	0.0005
CheckForPrime2	0.0006	0.0004	0.0003
CheckForPrime3	0.0006	0.0003	0.0003
CheckForPrime4	0.001	0.0006	0.0005
CheckForPrime5	0.0002	0.0002	0.0001*
CheckForPrime6	0.0002	0.0002	0.0001*

Searching from 100.000 to 200.000 (interval: 100.000)

Function	While	While skip ahead	For
CheckForPrime1	0.8063	0.7147	15.279
CheckForPrime2	12.418	11.394	24.082
CheckForPrime3	12.275	11.934	20.835
CheckForPrime4	2.385.757	2.484.423	3.407.217
CheckForPrime5	0.7796	10.944	10.462
CheckForPrime6	0.4709*	10.758	0.7892

Searching from 200.000 to 400.000 (interval: 200.000)

Function	While	While skip ahead	For
CheckForPrime1	13.967	0.991	0.9844
CheckForPrime2	24.884	14.276	15.029
CheckForPrime3	20.627	14.001	14.561
CheckForPrime4	4.267.062	3.728.232	3.509.704
CheckForPrime5	0.7277	0.6901	0.6733
CheckForPrime6	0.6428	0.5645	0.5591*

Searching from 10.000.000.000 to 10.000.100.000 (interval: 100.000)

Function	While	While skip ahead	For
CheckForPrime6	231.544	229.244	226.361*

Searching from 0 to 1.000.000 (interval: 1.000.000)

Function	While	While skip ahead	For
CheckForPrime6	20.672	18.981	18.986*

Searching from 1.000.000 to 2.000.000 (interval: 1.000.000)

Function	While	While skip ahead	For
CheckForPrime1	16.078	14.665	13.6017
CheckForPrime2	23.9532	21.5605	20.5047
CheckForPrime3	25.6407	21.091	20.1112
CheckForPrime4	12894.9781	12738.8425	12184.6509
CheckForPrime5	11.5815	11.2439	10.7628
CheckForPrime6	9.7153	9.0733*	9.0991

Searching from 0 to 100.000.000 (interval: 100.000.000)

Function	While	While skip ahead	For
CheckForPrime6	1352.1654	1340.9117	1321.2643*

Searching from 100.000 to 200.000 (interval: 100.000)

Function	While	While skip ahead	For
CheckForPrime6	0.1438	0.1228*	0.123