doobwa

# Borrowed from http://dirk.eddelbuettel.com/papers/rcpp_workshop_part_3_advanced.pdf

require(Rcpp)
require(inline)
require(testthat)

fx <- cxxfunction(,"",includes=
'
double norm( double x, double y ){
  return sqrt( x*x + y*y) ;

doobwa

# Chris DuBois
# October 2, 2011

# dfapply: apply an expression to each row of a data.frame

# This can be especially helpful when organizing experimental setups and you want to plot the results from a data.frame.

# s: data.frame, where each row has argument values 
# expr: expression to evaluate on each row of s

doobwa

log.sum.exp<- function(x) {
  # Computes log(sum(exp(x))
  # Uses offset trick to avoid numeric overflow: http://jblevins.org/notes/log-sum-exp
  offset <- x[which(x == max(abs(x)))]
  log(sum(exp(x - offset))) + offset
}