Sieve of Eratosthenes

[Albert Chan]

(12-19-2018 02:30 PM)Eddie W. Shore Wrote:  FOR K FROM 2 TO 7 DO
FOR R FROM 1 TO 7 DO
FOR C FROM 1 TO 7 DO
IF FP(M0(R,C)/K)==0 AND M0(R,C)>K THEN M0(R,C):=0; ...

I don't think the code is really a prime sieve.
A true sieve does not need any divisibility test.
Also, looping count is very high = 6x7x7 = 294

I think sieve should be like below code.
To get your 7x7 matrix, do list2mat(sieve(7*7), 7)

PHP Code:

sieve(n) := {
    local a, c, p, pmax;
    a := range(1, n+1); a(1) := 0;       // 1 is not prime
    pmax := floor(sqrt(n));
    for p from 2 to pmax do
        if (a(p) == 0) continue;         // skip composite
        for(c:=p*p; c<=n; c+=p) a(c):=0; // mark composite
    end;
    return a;
}