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Annotation of OpenXM_contrib/PHC/Ada/Schubert/maximal_minors.adb, Revision 1.1

1.1     ! maekawa     1: with Standard_Floating_Numbers_io;       use Standard_Floating_Numbers_io;
        !             2: with Standard_Natural_Vectors;           use Standard_Natural_Vectors;
        !             3: with Standard_Natural_Vectors_io;        use Standard_Natural_Vectors_io;
        !             4: with Standard_Floating_Linear_Solvers;   use Standard_Floating_Linear_Solvers;
        !             5:
        !             6: procedure Maximal_Minors ( file : in file_type;
        !             7:                            n,d : in natural; mat : in Matrix;
        !             8:                            min,max : out double_float ) is
        !             9:
        !            10:   function Determinant
        !            11:               ( mat : Matrix; rows : Standard_Natural_Vectors.Vector )
        !            12:               return double_float is
        !            13:
        !            14:   -- DESCRIPTION :
        !            15:   --   Computes the determinant of the matrix obtained by selecting rows.
        !            16:
        !            17:     res : double_float := 1.0;
        !            18:     sqm : Matrix(rows'range,rows'range);
        !            19:     piv : Standard_Natural_Vectors.Vector(rows'range);
        !            20:     inf : natural;
        !            21:
        !            22:   begin
        !            23:     for i in rows'range loop
        !            24:       piv(i) := i;
        !            25:       for j in rows'range loop
        !            26:         sqm(i,j) := mat(rows(i),j);
        !            27:       end loop;
        !            28:     end loop;
        !            29:     lufac(sqm,rows'last,piv,inf);
        !            30:     for i in rows'range loop
        !            31:       res := res*sqm(i,i);
        !            32:     end loop;
        !            33:     for i in piv'range loop
        !            34:       if piv(i) > i
        !            35:        then res := -res;
        !            36:       end if;
        !            37:     end loop;
        !            38:     return res;
        !            39:   end Determinant;
        !            40:
        !            41:   procedure Main is
        !            42:
        !            43:     rows : Standard_Natural_Vectors.Vector(1..d);
        !            44:     first : boolean := true;
        !            45:     mindet,maxdet : double_float;
        !            46:
        !            47:     procedure Select_Rows ( k,start : in natural ) is
        !            48:
        !            49:       det : double_float;
        !            50:
        !            51:     begin
        !            52:       if k > d
        !            53:        then det := Determinant(mat,rows);
        !            54:             put(file,"Minor "); put(file,rows); put(file," equals ");
        !            55:             put(file,det); new_line(file);
        !            56:             det := abs(det);
        !            57:             if first
        !            58:              then mindet := det; maxdet := det; first := false;
        !            59:              else if det > maxdet
        !            60:                    then maxdet := det;
        !            61:                    elsif det < mindet
        !            62:                        then mindet := det;
        !            63:                   end if;
        !            64:             end if;
        !            65:        else for j in start..n loop
        !            66:               rows(k) := j;
        !            67:               Select_Rows(k+1,j+1);
        !            68:             end loop;
        !            69:       end if;
        !            70:     end Select_Rows;
        !            71:
        !            72:   begin
        !            73:     Select_Rows(1,1);
        !            74:     put(file,"Min : ");       put(file,mindet,3,3,3);
        !            75:     put(file,"  Max : ");     put(file,maxdet,3,3,3);
        !            76:     put(file,"  Max/Min : "); put(file,maxdet/mindet,3,3,3); new_line(file);
        !            77:     min := mindet; max := maxdet;
        !            78:   end;
        !            79:
        !            80: begin
        !            81:   Main;
        !            82: end Maximal_Minors;