/// <summary>
 /// Evaluate Taylor expansion a derivative structure.
 /// </summary>
 /// <param name="delta">parameters offsets (&Delta;x, &Delta;y, ...)</param>
 /// <returns>value of the Taylor expansion at x + &Delta;x, y + &Delta;y, ...</returns>
 /// <exception cref="MathArithmeticException"> if factorials becomes too large</exception>
 public double taylor(params double[] delta)
 {
     return(compiler.taylor(data, 0, delta));
 }