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	Eine Klasse mit mathematischen Methoden (Lösung)

// ------------------------------ MathUtil.java ------------------------------- \\

public class MathUtil
{
   // ------------------------------- round() --------------------------------- \\
   public static double round(double x, int stellen)
   {
      double tmp = Math.pow(10,stellen) ;
      return Math.rint( tmp*x ) / tmp ;
      //return Math.rint( Math.pow(10,stellen)*x ) / Math.pow(10,stellen) ;
   }

   // -------------------------------- max() ---------------------------------- \\
   public static int max(int arr[])
   {
      int max = arr[0] ;

      for(int i=1; i<arr.length; i++)
         if (max<arr[i]) max = arr[i] ;

      return max;
   }

   // -------------------------------- max() ---------------------------------- \\
   public static double max(double arr[])
   {
      double max = arr[0] ;

      for(int i=1; i<arr.length; i++)
         if (max<arr[i]) max = arr[i] ;

      return max;
   }

   // -------------------------------- sgn() ---------------------------------- \\
   public static int sgn(double x)
   {
      return x>0 ? 1 : x<0 ? -1 : 0 ;
   }

   // -------------------------------- kgV() ---------------------------------- \\
   public static double kgV(int a, int b)
   {
      if (a*b==0) return 0 ;

      double max = a < b ? b : a ;
      double min = a < b ? a : b ;
      int i;

      for(i=1 ; (i*max)%min != 0 ; i++)
         ;

      return i*max ;
   }

   // -------------------------------- ggT() ---------------------------------- \\
   public static double ggT(int a, int b)
   {
      if (a*b==0) return 0 ;

      return a*b/ kgV(a,b) ;
   }

   // ------------------------------- fibo() ---------------------------------- \\
   public static double fibo(int n)
   {
      if (n < 0 || n > 92 )
         return -1 ;

      if (n<=1) return n;

      long fibo=0, vor=0, vorvor=1 ;

      vor = 0 ; vorvor = 1 ;
      for(int i=0; i<n ; i++ )
      {
         fibo = vor + vorvor ;
         vorvor = vor ;
         vor = fibo;
      }

      return fibo ;
   }

   // -------------------------------- fak() ---------------------------------- \\
   public static double fak(int n)
   {
      if (n<0) return Double.NaN ;
      if (n<=1) return 1;
      if (n>92) return Double.NaN ;

      double fak=1 ;

      for(int i=1; i<n; i++)
         fak = fak*(i+1) ;

      return fak;

   }

   // ------------------------------ isPrime() -------------------------------- \\
   public static boolean isPrime(long p)
   {
      if (p==0) return false;
      if (p<0) p = -p ;
      if (p==1) return false;
      if (p==2) return true;
      if (p%2==0) return false;

      for (int i=3 ; i<=Math.sqrt(p) ; i+=2)
         if (p%i==0)
            return false;

      return true;
   }

   // ------------------------------- binko() --------------------------------- \\
   public static double binko(int n, int v)
   {

      return 0 ;
   }

} // end class MathUtil