alexbrandmeyer@668: //
alexbrandmeyer@668: //  car_coeffs.cc
alexbrandmeyer@668: //  CARFAC Open Source C++ Library
alexbrandmeyer@668: //
alexbrandmeyer@668: //  Created by Alex Brandmeyer on 5/18/13.
alexbrandmeyer@668: //  Copyright (c) 2013 Alex Brandmeyer. All rights reserved.
alexbrandmeyer@668: //
alexbrandmeyer@668: 
alexbrandmeyer@668: #include "car_coeffs.h"
alexbrandmeyer@668: 
alexbrandmeyer@668: void CARCoeffs::Design(const CARParams& car_params, const FPType fs,
alexbrandmeyer@668:                         const FloatArray& pole_freqs) {
alexbrandmeyer@668:   // TODO (alexbrandmeyer): verify acceptability of/documentation level needed
alexbrandmeyer@668:   // for use of short intermediate variable names.
alexbrandmeyer@668:   n_ch_ = pole_freqs.size();
alexbrandmeyer@668:   velocity_scale_ = car_params.velocity_scale_;
alexbrandmeyer@668:   v_offset_ = car_params.v_offset_;
alexbrandmeyer@668:   r1_coeffs_.resize(n_ch_);
alexbrandmeyer@668:   a0_coeffs_.resize(n_ch_);
alexbrandmeyer@668:   c0_coeffs_.resize(n_ch_);
alexbrandmeyer@668:   h_coeffs_.resize(n_ch_);
alexbrandmeyer@668:   g0_coeffs_.resize(n_ch_);
alexbrandmeyer@668:   FPType f = car_params.zero_ratio_ * car_params.zero_ratio_ - 1.0;
alexbrandmeyer@668:   FloatArray theta = pole_freqs * ((2.0 * PI) / fs);
alexbrandmeyer@668:   c0_coeffs_ = theta.sin();
alexbrandmeyer@668:   a0_coeffs_ = theta.cos();
alexbrandmeyer@668:   FPType ff = car_params.high_f_damping_compression_;
alexbrandmeyer@668:   FloatArray x = theta / PI;
alexbrandmeyer@668:   zr_coeffs_ = PI * (x - (ff * (x*x*x)));
alexbrandmeyer@668:   FPType max_zeta = car_params.max_zeta_;
alexbrandmeyer@668:   FPType min_zeta = car_params.min_zeta_;
alexbrandmeyer@668:   r1_coeffs_ = (1.0 - (zr_coeffs_ * max_zeta));
alexbrandmeyer@668:   FloatArray erb_freqs(n_ch_);
alexbrandmeyer@668:   for (int ch=0; ch < n_ch_; ++ch) {
alexbrandmeyer@668:     erb_freqs(ch) = ERBHz(pole_freqs(ch), car_params.erb_break_freq_,
alexbrandmeyer@668:                           car_params.erb_q_);
alexbrandmeyer@668:   }
alexbrandmeyer@668:   FloatArray min_zetas = min_zeta + (0.25 * ((erb_freqs / pole_freqs) -
alexbrandmeyer@668:                                              min_zeta));
alexbrandmeyer@668:   zr_coeffs_ *= max_zeta - min_zetas;
alexbrandmeyer@668:   h_coeffs_ = c0_coeffs_ * f;
alexbrandmeyer@668:   FloatArray relative_undamping = FloatArray::Ones(n_ch_);
alexbrandmeyer@668:   FloatArray r = r1_coeffs_ + (zr_coeffs_ * relative_undamping);
alexbrandmeyer@668:   g0_coeffs_ = (1.0 - (2.0 * r * a0_coeffs_) + (r*r)) /
alexbrandmeyer@668:                                         (1 - (2 * r * a0_coeffs_) +
alexbrandmeyer@668:                                         (h_coeffs_ * r * c0_coeffs_) + (r*r));
alexbrandmeyer@668: }