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#!/bin/bash
# test1.sh

for N in {1..5000}; do
        A=$(bc -l <<< "scale=9; s(3.14159/$N)" &)
        B=$(bc -l <<< "scale=9; c(3.14159/$N)" &)
        wait
        printf "$A;$B\n"
done

#!/bin/bash
# test2.sh

function wait_for_threads() {
        while [ $(jobs -rp | wc -l) -ge $threads ];
                do sleep $check_interval_secs;
        done
}

threads=$(grep processor /proc/cpuinfo | wc -l)
check_interval_secs=0.01

for N in {1..5000}; do
        wait_for_threads
        (
                A=$(bc -l <<< "scale=9; s(3.14159/$N)")
                B=$(bc -l <<< "scale=9; c(3.14159/$N)")
                printf "$N $A;$B\n"
        ) &
done | sort -n | cut -d' ' -f2-

#!/bin/bash
# test3.sh

iters=5000

threads=$(grep processor /proc/cpuinfo | wc -l)
cluster_size=$((iters/threads))
last_cluster_size=$((iters-cluster_size*(threads-1)))

temp=$(mktemp -d)

for C in $(seq $threads); do
        
        first_iter=$(( (C-1) * cluster_size + 1 ))
        if [ $C -lt $threads ]; then
                last_iter=$(( first_iter + cluster_size -1 ))
        else
                last_iter=$(( first_iter + last_cluster_size -1 ))
        fi

        (
                for N in $(seq $first_iter $last_iter); do
                        A=$(bc -l <<< "scale=9; s(3.14159/$N)")
                        B=$(bc -l <<< "scale=9; c(3.14159/$N)")
                        printf "$A;$B\n"
                done
        ) > $temp/$C.list &
done

wait

for C in $(seq $threads); do
        cat $temp/$C.list
        rm $temp/$C.list
done

rmdir $temp

$ time ./test0.sh > test0.output # original bez paralelizace

real	0m15.776s
user	0m0.928s
sys	0m1.628s

$ time ./test1.sh > test1.output

real	0m12.012s
user	0m0.608s
sys	0m1.588s

$ time ./test2.sh > test2.output

real	0m11.803s
user	0m1.300s
sys	0m1.288s

$ time ./test3.sh > test3.output

real	0m3.278s
user	0m0.388s
sys	0m0.808s

$ for i in 1 2 3; do cmp test0.output test$i.output; echo $?; done
0
0
0