mat_mult.1<-function(a,b){
  newmat<-matrix(0:0,nrow(a),ncol(b))
if(nrow(a)!=ncol(b))
stop("non-conformable arguments")
  else{
for(i in 1:nrow(a))
  for(j in 1:ncol(b))
    for(k in 1:ncol(a))
          newmat[i,j]<-newmat[i,j]+a[i,k]*b[k,j]
  }
return(newmat)
}
mat_mult.1(matrix(0:8,3,6),matrix(1:9,3,3))