Weibull_mix.cpp

/* Weibull_mix.cpp */
#include <Rcpp.h> 
using Rcpp::NumericVector;

/* Computes the survival probability of a Weibull mixture. No checks are 
 * made on the length of the input vectors. */
// [[Rcpp::export]]
NumericVector Surv_Weibull_mix(
    NumericVector const t, NumericVector const ps, NumericVector const gs, 
    NumericVector const ls){
  std::size_t const n = t.size(), n_comp = ps.size();
  NumericVector out(n);
  
  for(std::size_t i = 0; i < n_comp; ++i){
    double const *to = &t[0L];
    for(auto o = out.begin(); o != out.end(); ++o, ++to)
      *o += ps[i] * std::exp(- ls[i] * std::pow(*to, gs[i]));
  }
  
  return out;
}