abstract public COSArray Eval(COSArray input) throws IOException
Evaluates the function at the given input.
ReturnValue = f(input)

 public static PDFunction create(COSBase function) throws IOException 
{
        PDFunction retval = null;
        if( function instanceof COSObject )
        {
            function = ((COSObject)function).getCOSObject();
        }
        if( function instanceof COSDictionary )
        {
            COSDictionary funcDic = (COSDictionary)function;
            int functionType =  funcDic.getInt( "FunctionType" );
            if( function instanceof COSStream )
            {
                if( functionType == 0 )
                {
                    retval = new PDFunctionType0(new PDStream((COSStream)function));
                }
                else if( functionType == 4 )
                {
                    retval = new PDFunctionType4(new PDStream((COSStream)function));
                }
                else
                {
                    throw new IOException( "Error: Unknown stream function type " + functionType );
                }
            }
            else
            {
                if( functionType == 2 )
                {
                    retval = new PDFunctionType2(funcDic);
                }
                else if( functionType == 3 )
                {
                    retval = new PDFunctionType3(funcDic);
                }
                else
                {
                    throw new IOException( "Error: Unknown dictionary function type " + functionType );
                }
            }
        }
        else
        {
            throw new IOException( "Error: Unknown COS type for function " + function );
        }
        return retval;
}

Create the correct PD Model function based on the COS base function.

 abstract public PDRange getDomainForInput(int n)
This will get the range for a certain input parameter.  This is will never
return null.  If it is not present then the range 0 to 0 will
be returned.

 abstract public int getNumberOfInputParameters()
This will get the number of input parameters that
have a domain specified.

 abstract public int getNumberOfOutputParameters()
This will get the number of output parameters that
have a range specified.  A range for output parameters
is optional so this may return zero for a function
that does have output parameters, this will simply return the
number that have the rnage specified.

 abstract public PDRange getRangeForOutput(int n)
This will get the range for a certain output parameters.  This is will never
return null.  If it is not present then the range 0 to 0 will
be returned.

 abstract public  void setDomainForInput(PDRange range,
    int n)
This will set the domain for the input values.

 abstract public  void setRangeForOutput(PDRange range,
    int n)
This will set the a range for output parameter.