Is you sqrt function even made? If not then you should make it. If you have
made the function sqrt, you probably have made it static since you want to
reference from inside the main function. Unfortunately Java doesnt allow
that.

Just going to elaborate on what I said:
You can't use the arithmetic operators you would normally use on primitives
(i.e. double) on objects (i.e. Double). eg 1 + sqrt(4).
If you have made the function sqrt then you can make the function return an
int or similar. In that way Java will know what the return is
and the operator can then be applied.

Also I made the mistake of telling you that you cant reference anything in a
static context. That is still true but from main you can call static methods
which will resolve your problem e.g.

class tal {
 public static void main(String[] arguments) {
   for (int i=0; i<11; i++) {
     System.out.println(i + ": " + sqrt(4));
   }
 }
   public static int sqrt(int a){
      // do something here with a

   return 1;
   }
}

Just remember that you can only use the variables given as parameters and
locally declared variables in a static method.
You can use the return value

Try this:

class tal
{
    public static void main(String[] arguments)
    {
        for (int i = 0; i < arguments.length; i++)
        {
            System.out.println(i + ": " +
                    java.lang.Math.sqrt(Double.parseDouble(arguments[i])));
        }
    }
}

Thanks in Advance...
IchBin, Pocono Lake, Pa, USA              http://weconsultants.phpnet.us
__________________________________________________________________________

'If there is one, Knowledge is the "Fountain of Youth"'
-William E. Taylor,  Regular Guy (1952-)

Thank you to all of you for helpfull advice ;-)
/Bjorn