day30

%% Set independent frequency vector
% needs to cover the "special" frequency of 12

%            /-- start at w=0
%            |   /-- end at 1200 rad/s
%            |   |      /-- this many items
w = linspace(0, 1200, 1000);


%% Compute the complex-valued transfer function
% The transfer function example
%   Mind the difference between "/" and "./" !
%   If in doubt, always use "./" and ".*" and " .' "
A = 35 ./ (1 + 1j*w / 12);


%% Plot to see the *magnitude*
plot(w, abs(A))
labels('V/V')


%% Log-space the x-axis (frequency) only
semilogx(w, abs(A))
labels('V/V')

%% Log-space both axes to look even more familiar
loglog(w, abs(A))
labels('V/V')


%% Use decibels for the vertical axis
Amag_dB = 20*log10(abs(A));

% y-axis is *already* log-spaced, so only log-space the x-axis
semilogx(w, Amag_dB)
labels('dB')

fprintf("\nMax gain %.1f V/V\n", max(abs(A)))
fprintf("Max gain %.1f dB\n", max(Amag_dB))


%% Helper functions

% Label the plot and add grid
function labels(y_units)
    grid('on')
    xlabel("Frequency \omega")
    ylabel(["Magnitude |A| ", y_units])
    title("Transfer function")
end