Replace all values in a matrix <0.1 with 0

Question

I have a matrix (2601 by 58) of particulate matter concentration estimates from an air quality model. Because real-life air quality monitors cannot measure below 0.1 ug/L,

Answer 1

A data.frame solution:

if(!require(plyr)){
    install.packages("plyr")}

rm.neg<-colwise(function(x){
  return(ifelse(x < 0.1, 0, x))})

rm.neg(data.frame(mat))

PS: the code for rm.neg can be extracted and simplified so as not to need a call to plyr, which is used to create the colwise function.