%
% Written by:
% -- 
% John L. Weatherwax                2009-04-21
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

clc; close all; clear; 

M_q = -0.568;
M_alpha = -17.98; % negated from books number
L_alpha_over_V = 1.237;
M_dE = -0.175; % negated from books number
L_dE_over_V = 0.001;

w_n = sqrt( -M_alpha )

xi = ( 0.5/(w_n) ) * ( L_alpha_over_V - M_q )

Nw     = 1000;
wArray = linspace(0,+70,Nw);
A      = zeros(1,Nw);
P      = zeros(1,Nw);
for wi = 1:Nw,
  w  = wArray(wi);
  vn = ( i * w + L_alpha_over_V ) * M_dE - M_alpha * L_dE_over_V;
  vd = -w^2 + 2 * i * xi * w_n * w + w_n^2;
  v  = vn/vd;
  
  A(wi) = 20*log(abs(v));
  P(wi) = angle(v)*(180/pi);
  
end

figure; 
plot( wArray, A, '-' );
xlabel('omega (radians)'); ylabel('20 log(A(w))');
%saveas( gcf, '../../WriteUp/Graphics/Chapter2/sect_6_prob_1_part_c_N_d_A.eps', 'epsc' );

figure;
plot( wArray, P, '-' );
xlabel('omega (radians)'); ylabel('phi(w) (deg)');

%saveas( gcf, '../../WriteUp/Graphics/Chapter2/sect_6_prob_1_part_c_N_d_P.eps', 'epsc' );