using System;

public class Program

{

    private static bool IsMultipleOf(double numerator, double denominator)

    {

        if (denominator <= 0 || numerator <= 0)

        {

            return false;

        }

​

        var res = numerator / denominator;

        return Math.Abs(res - Math.Round(res)) < 1e-9;

    }

    public static double modulo( double a, double b, double num_sig_digits = 14 )

{

   double  int_closest_to_ratio

         , abs_val_of_residue

         ;

​

   if ( double.IsNaN( a )

      || double.IsNaN( b )

      || 0 == b

      )

   {

      throw new Exception( "function modulo called with a or b == NaN or b == 0" );

   }

​

   if ( b == Math.Floor( b ) )

   {

      return (a % b);

   }

   else

   {

      int_closest_to_ratio = Math.Round( a / b );

      abs_val_of_residue = Math.Abs( a - int_closest_to_ratio * b );

      if ( abs_val_of_residue < Math.Pow( 10.0, -num_sig_digits ) )

      {

         return 0.0;

      }

      else

      {

         return abs_val_of_residue * Math.Sign( a );

      }

   }

}

​

    public static void Main()

    {

        Console.WriteLine(IsMultipleOf(0.03,0.01000001));

        Console.WriteLine(IsMultipleOf(0.03,0.0100000000000001));

        Console.WriteLine(modulo(0.03,0.01000001));

        Console.WriteLine(modulo(0.03,0.0100000000000001));

        Console.WriteLine(modulo(0.03,0.01));

    }

}