Inconsistent behavior for `psi` relaxation for `s1` and `s2`

[raui100]

I've stumbled upon the following incosistency: Given the arrays double s1[] = {0.0, 1.0}, double s2[] = {0.0, 0.0} and DTWSettings settings = dtw_settings_default() I would expect the following code to produce the same results.
However 1. calculates 1.0 and 2. calculates 0.0. Is this correct and expected?

1. settings.psi_1e = 1;
   double d = dtw_distance_ndim_euclidean(s1, 2, s2, 2, 1, &settings);

2. settings.psi_2e = 1;
   double d = dtw_distance_ndim_euclidean(s1, 2, s2, 2, 1, &settings);

C test code

```c Test(dtw_psi, test_a_d) { double s1[] = {0.0, 1.0}; double s2[] = {0.0, 0.0}; DTWSettings settings = dtw_settings_default(); settings.psi_1e = 1; double d = dtw_distance_ndim_euclidean(s1, 2, s2, 2, 1, &settings); cr_log_warn("%f", d); cr_assert_float_eq(d, 1.0, 0.001); } Test(dtw_psi, test_a_e) { double s1[] = {0.0, 0.0}; double s2[] = {0.0, 1.0}; DTWSettings settings = dtw_settings_default(); settings.psi_2e = 1; double d = dtw_distance_ndim_euclidean(s1, 2, s2, 2, 1, &settings); cr_log_warn("%f", d); cr_assert_float_eq(d, 0.0, 0.001); } ```

[wannesm]

Thanks for the report and useful example. There was indeed a bug in the distance function for psi_1e. Fix available in the master branch.

However, code 1 and code 2 are expected to give different results.

Code 1 should return 0.0 and code 2 returns 1.0. If psi_1e is set to 1, the last value in the first series can be ignored. In this case that is a 1.0 that would be mapped to a 0.0. The result is thus 0.0 instead of 1.0. If psi_2e is set to 1, the last value in the second series can be ignored. But this last value is 0.0, same like the first value. The 1.0 in the second series is thus still aligned to a 0.0 with a difference of 1.0. The result is thus 1.0.

[raui100]

Thank you so much for the work you put into this library :) And thanks a bunch for the explanation...