TABLE OF CONTENTS

CmakeLikelihood/LikelihoodFrailtyLogSum [ Functions ]

NAME

    LikelihoodFrailtyLogSum --- utility to efficiently compute a sum of log-frailties

FUNCTION

Because the log function is quite slow (especially it seems on the MacIntel architecture), this function computes the sum of log-frailties by multiplying several together at a time, then taking logs.

SYNOPSIS

1648 static inline double LikelihoodFrailtyLogSum(int nx, double *Y)

INPUTS

    nx        number of observations
    Y         vector of length nx

OUTPUTS

    lik       sum of log(Y)

SOURCE

1652 {
1653     double lik=0;
1654     double thislik = 1;
1655 
1656     for(int i=0; i<nx; i++) {
1657         thislik *= Y[i];
1658         if(i % LIK_MOD == 0){
1659             lik += log(thislik);
1660             thislik = 1;
1661         }
1662     }
1663     lik += log(thislik);
1664     return lik;
1665 }