Philip Rowlands wrote: > The conversion of everything to long doubles internally makes seq a lot > slower than it needs to be in integer cases, I assume from the use of > floating-point multiplication for every line of output: > > seq.c:257 x = first + i * step; > > $ time seq 1000000 > /dev/null > > real 0m1.616s > user 0m1.610s > sys 0m0.004s > > > $ time ./myseq 1000000 > /dev/null > > real 0m0.280s > user 0m0.275s > sys 0m0.005s > > > Would it be possible to detect arguments which require no > floating-point, and handle them with integer addition?
I've noticed that too, but it wasn't on my priority list. Here are some alternatives and timings: $ time seq 1000000 > /dev/null real 0m1.236s $ time yes '' | nl -ba -w1 -s' ' | head -n1000000 > /dev/null real 0m0.623s $ time shuf -i 1-1000000 --random-source=/dev/zero > /dev/null real 0m0.568s # This uses ascii add from getlimits.c and is arbitrary precision $ time seq2 1 1 1000000 > /dev/null real 0m0.379s # simple for(...) printf(i); $ time seq.simple > /dev/null real 0m0.268s # cat -n uses ascii add optimised for +1 case (next_line_num) $ time yes '' | cat -n | head -n1000000 > /dev/null real 0m0.142s cheers, Pádraig.
