The progress of all technology, including nanotechnology, is driven by developments in applied mathematics which would include but not be limited to digital signal processing, discrete mathematics, and numerical methods and analysis. Mathematical methods have an important role to play in all aspects of system design and simulation, and the processing of data generated by systems.
NOTES: The solution depicted in Fig. 1 (NDT3-04-2006) is not the true globally optimal solution for the stated constraints. If differential evolution is allowed to run for more generations then the result will be (or be close to) a = [ 0.43157974 0.76443945 0.05831938 ]. For this parameter vector the worst-case approximation error is about 0.00035°. However, the solution in Fig. 3 is unaffected by this. Exhaustive search of all possible parameter vectors confirms that the solution in Fig. 3 is the globally optimal solution given the stated constraints. A convergence analysis, and a prescription to avoid differential evolution algorithm stagnation appear in D. Zaharie, "Critical Values for the Control Parameters of Differential Evolution Algorithms," Proc. of Mendel 2002, 8th Int. Conf. on Soft Computing, Brno, Czech Republic, pp. 62-67. A noteworthy update about arctangent computation appears in S. Rajan, S. Wang, R. Inkol, A. Joyal, "Efficient Approximations for the Arctangent Function," IEEE Signal Processing Magazine, May 2006, pp. 108-111.
NOTES: Refer to NDT7-01-2007. An alternative means to obtain state vector a(n) from a(n+1) is as follows. We are given that ai(n+1) is known for all i = 0,1, ... ,N-1, and if we knew 'starter bits' ai(n) for i = N-1, and N-2 then all remaining bits of the state vector a(n) can be found by executing the recursion ai-1(n) = ai(n) + ai+1(n) + ai(n) ai+1(n) + ai(n+1) for i = N-2,N-3, ... , 2,1. (Here the operations are understood to be modulo 2.) If we do not know the starter bits then we may simply guess. There are four possible choices. Try each in turn generating four possible solutions for a(n). Use each candidate solution to create a(n+1) by running cellular automaton Rule 30. Each such result may be compared with the already known vector a(n+1), and this allows us to determine which of the four possible choices for a(n) was the correct one. This approach will also detect a Garden-of-Eden state.
However, the algorithm in NDT7-01-2007 generates two quadratics in the two unknowns (starter bits) x1, and x2 (respectively, a0(n), and a1(n)) in O(N) time (see Equations (4.9), and (4.10)). A constant number of operations solves them yielding no more possibilities than are strictly necessary. Empirical evidence suggests that there are never more than two solutions (i.e., less than four possibilities), but a rigorous proof of this appears to be lacking. Knowing these starter bits allows for finding all remaining bits x3, ... ,xN (that is, a2(n), ... ,aN-1(n)) in O(N) time.
NOTES: In NDT16-08-2007 W (channel width), and L (channel length) are interpreted to be in microns.