Find the index of the value in a vector that is grater than a given constant
[sim, index] = ld_vector_findthr(sim, events, in, thr, greater, vecsize)
in *+(vecsize) - input
thr * - threshold signal
index * - output
find values greater than threshold "thr" in vector signal "in", when greater > 0
find values less than threshold "thr" in vector signal "in", when greater =< 0