view matlab/bmm/carfac/CARFAC_Spatial_Smooth.m @ 611:0fbaf443ec82

Carfac C++ revision 3, indluding more style improvements. The output structs are now classes again, and have separate storage methods for each output structure along with flags in the Run and RunSegment methods to allow for only storing NAPs if desired.

% Copyright 2012, Google, Inc.
% Author: Richard F. Lyon
%
% This Matlab file is part of an implementation of Lyon's cochlear model:
% "Cascade of Asymmetric Resonators with Fast-Acting Compression"
% to supplement Lyon's upcoming book "Human and Machine Hearing"
%
% Licensed under the Apache License, Version 2.0 (the "License");
% you may not use this file except in compliance with the License.
% You may obtain a copy of the License at
%
%     http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS,
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
% See the License for the specific language governing permissions and
% limitations under the License.

function stage_state = CARFAC_Spatial_Smooth(coeffs, stage, stage_state)
% function AGC_state = CARFAC_Spatial_Smooth( ...
%   n_taps, n_iterations, FIR_coeffs, AGC_state)

n_iterations = coeffs.AGC_spatial_iterations(stage);

use_FIR = n_iterations < 4;  % or whatever condition we want to try

if use_FIR
  FIR_coeffs = coeffs.AGC_spatial_FIR(:,stage);
  switch coeffs.AGC_spatial_n_taps(stage)
    case 3
      for iter = 1:n_iterations
        stage_state = ...
          FIR_coeffs(1) * stage_state([1, 1:(end-1)], :) + ...
          FIR_coeffs(2) * stage_state + ...
          FIR_coeffs(3) * stage_state([2:end, end], :);
      end
    case 5  % 5-tap smoother duplicates first and last coeffs:
      for iter = 1:n_iterations
        stage_state = ...
          FIR_coeffs(1) * (stage_state([1, 2, 1:(end-2)], :) + ...
          stage_state([1, 1:(end-1)], :)) + ...
          FIR_coeffs(2) *  stage_state + ...
          FIR_coeffs(3) * (stage_state([2:end, end], :) + ...
          stage_state([3:end, end, end-1], :));
      end
    otherwise
      error('Bad AGC_spatial_n_taps in CARFAC_Spatial_Smooth');
  end
else
  % use IIR method, back-and-forth first-order smoothers:
  stage_state = SmoothDoubleExponential(stage_state, ...
    coeffs.AGC_polez1(stage), coeffs.AGC_polez2(stage));
end