TwoArrayFun

library(magrittr)

A <- matrix( c(1:48000),ncol = 1600 );
B <- matrix( c(1:8000),ncol = 1600 );

FUN = function(a,b){
  return(as.matrix(a) %*% t(b))
}

C=lapply( 1:ncol(A) , function(x) FUN( A[,x],B[,x] ) ) %>% simplify2array