rlba_norm used the LBA process to generate response times and
responses.
rlba_norm(n, A, b, mean_v, sd_v, t0, st0, posdrift)a n x 2 matrix of response time (first column) and responses (second column).
is the numbers of observation.
start point upper bound, a vector of a scalar.
decision threshold, a vector or a scalar.
mean drift rate vector
standard deviation of drift rate vector
non-decision time, a vector.
non-decision time variation, a vector.
if exclude negative drift rates