Doself2 vectorisation

Implements:

• runner_doself2_force_vec a vectorised version of the DOSELF2 for force interactions.
• Updates particle cache with properties needed for force interactions.
• Vectorised interaction functions for the force using 1 and 2 vectors, which are tested in testInteractions.c

I guess you know what I am going to ask...

Not a very clear comment. Particles can interact if dx > h the kernel should then return 0.

I think what you mean is that the result will be garbage if the function is called with dx > h.

Yep haha. Tested for accuracy with EAGLE_12 and EAGLE_25.

How about:

/**
* @brief Computes the kernel function and its derivative for two particles
* using vectors. The return value is undefined if $u > \\gamma = H/h$, should only
* be called if particles are known to interact.

I have just tried computing the interaction on the fly without the interaction cache and it goes 2.1x faster than the serial. So can we wait before merging it with the master?

Yes.

I would even drop everything after the comma.

Added 2 commits:

• 3b1777d3 - Pass hj_inv as a vector instead of a pointer.
• d58babff - Created new version of doself2_vec that computes force interaction on the fly, 2…

Added 2 commits:

• a766a9a2 - Removed alternate version of doself2_vec that was slower than current version. R…
• 1bfcfaf6 - Updated comments.

Fixed in 1bfcfaf6.

Added 1 commit:

• 614928e3 - Removed unneeded force properties in interaction cache.

How do you feel about values that cause floating point exceptions but are masked out in the interaction?

Does it lead to a crash if you run with -e ?

Yes

But it produces correct results with EAGLE_12.

Ok, but that's not great. Means we can't debug anything with -e anymore since your vectorized code will trigger false positives all the time.

Yeah, true. I'll add something to stop it from happening.

How about:

v_r2.v = vec_add(v_r2.v, vec_set1(FLT_MIN));

Added 3 commits:

• 442892a3 - Reset particles.
• 547fb37f - Account for separations of zero.
• 706138ac - Formatting.

Won't that make the particles interact ?