| draw_U | Samples from a Multivariate Normal Distribution | 
| eval_marker | Fast Evaluation of Time-varying Marker Mean Term | 
| eval_surv_base_fun | Evaluates the Survival Function without a Marker | 
| get_gl_rule | Get Gauss–Legendre Quadrature Nodes and Weights | 
| get_ns_spline | Faster Pointwise Function than ns | 
| sim_joint_data_set | Simulate Individuals from a Joint Survival and Marker Model | 
| sim_marker | Simulate a Number of Observed Marker for an Individual | 
| surv_func_joint | Evaluates the Conditional Survival Function Given the Random Effects |