The Sinclair QL Forum

Code: Select all

 #define N 200000

 #include <stdio_h>
 #include <math_h>
 #include <stdlib_h>
 #include <time_h>

 char *crossed;
 long i, j, k;

 void main () {
    time_t t;
    t = time (NULL);
    crossed = calloc (N, 1);

    for (i = 2; i < sqrt(N); i++) {
       if (!*(crossed + i)) {
          printf ("%d, ", i);
          for (j = i*i; j < N; j+=i) {
             *(crossed + j) = 1;
          }
       }
    }

    for (i = sqrt(N) + 1; i < N; i++) {
       if (!*(crossed + i)) {
          printf("%d, ", i);
       }
    }
    printf("Primes to %d calculated in %d seconds", N, time (NULL) - t);
}

Code: Select all

10 a = DATE
100  DEF_INTEGER i,j
110  MANIFEST: n = 200000
120  crossed = ALCHP (n)
140  FOR i = 1 TO n
150    POKE crossed+i, 0
160  END FOR i
180  REMark sieve
190  FOR i = 2 TO SQRT(n)
200    IF PEEK(crossed+i) = 0 THEN
210      PRINT i; ", ";
220      FOR j = i * i TO n STEP i
230        POKE crossed+j, 1
240      END FOR j
250    END IF
260  END FOR i
280  FOR i = INT(SQRT(n)) + 1 TO n
290    IF PEEK(crossed +i) = 0
300      PRINT i; ", ";
310    END IF
320  END FOR i
330 PRINT :PRINT "Primes to ";n;" calculated in "; DATE - a; " seconds"
335 PAUSE -1
337 RECHP crossed
340  STOP

Code: Select all

..
100  DEF_INTEGER i,j
110  MANIFEST: n = 200000
120  crossed = ALCHP (n)
140  FOR i = 1 TO n
..