fixes STIR TOF AcquisitionData algebra

[KrisThielemans]

inserted TOF loops. However, this needs the STIR_TOF preprocessor variable to be defined, which is still to be merged on the STIR TOF branch.

[evgueni-ovtchinnikov]

Will this be backward compatible? If not, should this not be merged after data-cont-templ?

[evgueni-ovtchinnikov]

suggestion:

#define TOF_LOOP(k) for(int k=...)
#define TOF_ARG(k) , k
#else
#define TOF_LOOP(k)
#define TOF_ARG(k)

[KrisThielemans]

It should be once I'm done (had some stupid errors!). All changes should be within #ifdef STIR_TOF. If you don't build with it, everything should be identical.

[KrisThielemans]

@evgueni-ovtchinnikov currently some of the tests fail due to numerical rounding error. Printing stuff like

 print('norm:', s, t, eps, abs(t-s), eps*abs(t))

after

SIRF/src/common/Utilities.py

Line 600 in 1bb1b11

test.check_if_equal(1, abs(t - s) <= eps * abs(t))

I get

+++ test 0 failed: expected 1, got False
norm: 47163.3984375 47161.4 1e-05 2.0 0.471613984375
+++ test 1 passed
+++ test 2 passed
+++ test 3 failed: expected 1, got False
dot: 68452680.0 68447064.0 1e-05 5616.0 684.47064
+++ test 4 passed
+++ test 5 passed

etc (2 more tests are failing, not sure yet which).

Your implementations look ok though, they use double for the temp variable (see e.g. here). I guess we could increase our tolerance a bit?

Aside from that, it's annoying that these tests don't give any feedback about failure and I had to add the print by hand. Easy to replace with check_if_equal_within_tolerance`?

[KrisThielemans]

note that the above failure is on some TOF data (I haven't run on non-TOF yet, but Actions will tell us)

[evgueni-ovtchinnikov]

can you please try

	return (float)std::sqrt(t);

in norm() instead of

	return std::sqrt((float)t);

[KrisThielemans]

@evgueni-ovtchinnikov that does indeed look better but it didn't make any practical difference. It could indeed be that the numpu.linalg.norm isn't as smart as we are 😄 . In any case, the difference is well below our precision.

I've now

• modified the tests to
  • relax it for norm and dot
  • use check_if_..._tolerance for clearer output if they fail.
• changed norm to do what you suggest, but I also rewrote the loop, such that it's far shorter. Finally, I used stir::norm_squared to save 2 lines (sadly had to modify an unrelated line using stir::norm due to a STIR bug). This could be done for the others as well, but I have run out of time.

I'm done with this therefore and would like to merge. Can you have a look please?

[KrisThielemans]

@NicoleJurjew, this is now merged to SIRF master