Erlang/OTP Forums

-export([primzahlen/2]).
-export([modulo/2]).

primzahlen(bis) when bis > 1 ->
            primzahlen(2, bis).

primzahlen(von, bis) when von < bis ->
    is_prim = istPrim(von),
    if
        is_prim ->
            io:fwrite("später die ausgabe von von")
    end,
    primzahlen(von+1,bis).

istPrim(z) when z < 2 -> false;
istPrim(z) -> istPrim(2,math:sqrt(z)).

istPrim(i, z) when i==z -> true;
istPrim(i, z) when i<z ->
    is_rfd = modulo(z, i),
    if
        is_rfd == 0 ->
            false;
        true ->
            istPrim(i+1,z)
    end.

modulo(a,b) ->
    z = trunc(a/b),
    if z*b == a -> true;
    true -> false
    end.

c(prim).         
./prim.erl:9: Warning: no clause will ever match
./prim.erl:9: Warning: the guard for this clause evaluates to 'false'
./prim.erl:11: Warning: no clause will ever match
./prim.erl:12: Warning: the guard for this clause evaluates to 'false'
./prim.erl:15: Warning: this expression would cause a 'badarith' exception at run-time
./prim.erl:17: Warning: the guard for this clause evaluates to 'false'
./prim.erl:20: Warning: the guard for this clause evaluates to 'false'
./prim.erl:24: Warning: the guard for this clause evaluates to 'false'
./prim.erl:27: Warning: this expression would cause a 'badarith' exception at run-time
./prim.erl:31: Warning: this expression would cause a 'badarith' exception at run-time
./prim.erl:32: Warning: this expression would cause a 'badarith' exception at run-time
{ok,prim}
 prim:primzahlen(10).

=ERROR REPORT==== 9-Apr-2008::14:01:12 ===
Error in process <0.196.0> with exit value: {function_clause,[{prim,primzahlen,"\n"},{erl_eval,do_apply,5},{shell,exprs,6},{shell,eval_loop,3}]}

** exited: {function_clause,[{prim,primzahlen,"\n"},
                             {erl_eval,do_apply,5},
                             {shell,exprs,6},
                             {shell,eval_loop,3}]} **