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Annotation of OpenXM_contrib/PHC/Ada/Root_Counts/Symmetry/permutations.adb, Revision 1.1

1.1     ! maekawa     1: package body Permutations is
        !             2:
        !             3:   function Is_Permutation ( p : Permutation ) return boolean is
        !             4:   begin
        !             5:     for i in p'range loop
        !             6:       if ((p(i) = 0) or else (p(i) < -p'last) or else (p(i) > p'last))
        !             7:        then return false;
        !             8:        else for j in p'first..(i-1) loop
        !             9:               if ((p(i) = p(j)) or else (p(i) = -p(j)))
        !            10:                then return false;
        !            11:               end if;
        !            12:             end loop;
        !            13:       end if;
        !            14:     end loop;
        !            15:     return true;
        !            16:   end Is_Permutation;
        !            17:
        !            18:   function Equal ( p1,p2 : Permutation ) return boolean is
        !            19:   begin
        !            20:     if (p1'first /= p2'first) or else (p1'last /= p2'last)
        !            21:      then return false;
        !            22:      else for i in p1'range loop
        !            23:             if p1(i) /= p2(i)
        !            24:              then return false;
        !            25:             end if;
        !            26:           end loop;
        !            27:           return true;
        !            28:     end if;
        !            29:   end Equal;
        !            30:
        !            31:   function "*" ( p1,p2 : Permutation ) return Permutation is
        !            32:
        !            33:     r : Permutation(p1'range);
        !            34:
        !            35:   begin
        !            36:     for i in r'range loop
        !            37:       if p2(i) >= 0
        !            38:        then r(i) := p1(p2(i));
        !            39:        else r(i) := -p1(-p2(i));
        !            40:       end if;
        !            41:     end loop;
        !            42:     return r;
        !            43:   end "*";
        !            44:
        !            45:   function inv ( p : Permutation ) return Permutation is
        !            46:
        !            47:     r : Permutation(p'range);
        !            48:
        !            49:   begin
        !            50:     for i in r'range loop
        !            51:       if p(i) >= 0
        !            52:        then r(p(i)) := i;
        !            53:        else r(-p(i)) := -i;
        !            54:       end if;
        !            55:     end loop;
        !            56:     return r;
        !            57:   end inv;
        !            58:
        !            59: end Permutations;