Provides the boundary, collapsing in accordance with a Weibull function
b_weibull(prms_model, prms_solve, t_vec, one_cond, ddm_opts)dt_b_weibull(prms_model, prms_solve, t_vec, one_cond, ddm_opts)
a vector of the same length as t_vec with the boundary values (or the deriviative) for each element of the vector.
the model parameters, containing b0, lambda, k, kappa
solver settings
time space
one condition
optional arguments attached to an object
b_weibull and dt_b_weibull provide the plain boundary values and the
respective derivative, respectively.