Transpose matrix in awk

transpose.awk

{   
    for (i = 1; i <= NF; i++)  {
        a[NR,i] = $i
    }
}
NF > p { p = NF }
END {
    for (j = 1; j <= p; j++) {
        str = a[1,j]
        for (i = 2; i <= NR; i++) {
            str = str"\t"a[i,j];
        }
        print str
    }
}

$ time awk -f transpose.awk random.mtx > random.mtx.transpose-awk

real    0m17.362s
user    0m15.127s
sys     0m1.881s

$ time mawk -f transpose.awk random.mtx > random.mtx.transpose-mawk

real    0m40.647s
user    0m38.856s
sys     0m1.388s