= Distance Calculation Comparison =

This is a comparison between the two methods of distance calculations in OpenSHA.

The two options (both in [source:trunk/src/org/opensha/commons/geo/LocationUtils.java LocationUtils.java] are linearDistance (referred to as "slow") and linearDistanceFast (referred to as "fast").

Test conducted with this class: [source:trunk/dev/scratch/kevin/DistSpeedTest.java]

For full results, see attachment dist_calc_comparison.xlsx

== Test Results ==

* Distance calculations: 5000000
* Distance range: 0.001 KM -> 5000 KM, 0.001 KM increments from starting location with azimuth of 45 degrees.
* Total times
 * Fast: 5463 milis = 5.463 secs (0.0010926 milis/calc)
 * Slow: 7410 milis = 7.410 secs (0.001482 milis/calc)
* Speedup: 1.356397583745195 x

||distance||dist delta (fast - slow)||percent difference||
||50 KM||1.28E-04 KM||2.57E-04 %||
||100 KM||0.001026994 KM||0.001027005 %||
||200 KM||0.008215952 KM||0.004108145 %||
||500 KM||0.128369704 KM||0.025680531 %||
||1000 KM||1.026777967 KM||0.102783287 %||
||2000 KM||8.207860832 KM||0.412083308 %||
||3000 KM||27.66526207 KM||0.930752669 %||
||4000 KM||65.46170846 KM||1.663744154 %||
||5000 KM||127.6116548 KM||2.61896699 %||

== Charts ==
=== Total cumulative calculation time over iterations ===
[[Image(dist_calc_time_chart.png)]]

=== Distance delta (fast distance - slow distance) vs calculation distance ===
[[Image(fast_minus_slow_chart.png)]]

=== Percent difference between fast and slow methods vs calculation distance ===
[[Image(percent_diff_chart.png)]]