Calculate distance between 2 lat longs

I have 4 columns in my data frame lat1,long1...lat2,long2. I need to calculate distance between these pairs. I am trying to use Distm function.

When I try to use distm (c(mydata2$lst_upd_longitude,mydata2$lst_upd_latitude), c(mydata2$long,mydata2$lat), fun = distHaversine)

R throws up an error "Error in .pointsToMatrix(x) : Wrong length for a vector, should be 2" For now I am using the below code to calculate distance for every point. But I am sure there should be a better solution. Also this code consumes lot of time.

for( i in 1:nrow(mydata2)){
  mydata2$distance[i] <- distm (c(mydata2$lst_upd_longitude[i],mydata2$lst_upd_latitude[i]), 
                                c( mydata2$long[i],mydata2$lat[i]), 
                                fun = distHaversine)}

Solution

Try

df <- read.table(sep=",", col.names=c("lat1", "lon1", "lat2", "lon2"), text="
52,4,52,13 
39,116,52,13")
library(geosphere)
distHaversine(df[, 2:1], df[, 4:3]) / 1000 # Haversine distance in km