boennecd

/* 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){

boennecd

#####
# simple version which stores the indices in a full matrix and then copy 
# them back later
f1 <- function(n){
  stopifnot(is.integer(n), n > 1L)
  nq <- n * (n + 1L) / 2L

  o <- matrix(0L, n, n)
  o[lower.tri(o, diag = TRUE)] <- 1:nq
  o[upper.tri(o)] <- t(o)[upper.tri(o)]