f_logo.m

DSP程序 Matlab是一套用于科学工程计算的可视化高性能语言与软件环境。它集数值分析、矩阵运算、信号处理和图形显示于一体

function f_logo (caption,instructor)

% F_LOGO: Draw FDSP logo of a comb filter transfer function
%
% Usage: f_logo (caption,instructor)
%
% Inputs:
%         caption    = title to display under logo 
%         instructor = optional integer.  When present and
%                      nonzero, this is an instructor's version

% Initialize

if nargin < 1
    caption = '';
end
if nargin < 2
    instructor = 0;
end

% Compute A = |H(z)|

dB = 0;
hmin = -80;
r = 0.9;
N = 4;
p = 81;
a = 2.0;
hmax = 2;
A = zeros(p,p);
zr = linspace(-a,a,p);
zi = zr;
h = waitbar (0,'Computing transfer function surface');
for i = 1 : p
   waitbar ((i-1)/(p-1),h);
   for k = 1 : p
      z = zr(i) + j*zi(k);
      A(i,k) = min(abs(z^N/(z^N-r^N)),hmax);
      if dB
          A(i,k) = max(20*log10(A(i,k)),hmin);
      end
   end
end
close (h)

% Plot it

mver = f_version('MATLAB');
if mver <= 6.1
    warning off
end
hs = surfc (zi,zr,A);
if mver < 7.0
   pause(0.01)                    % somehow needed to get clean plot?
   hs = surfc (zi,zr,A);
end

if mver <= 6.1
    warning on
end 
axis off

% Add captions

if ~instructor
    h_cap = text (0,0,-.8,caption);
    set (h_cap,'HorizontalAlignment','center',...
              'FontSize',28,...
              'FontAngle','oblique',...
              'Color','b');
else
    h_cap = text (0,0,-0.7,caption);
    set (h_cap,'HorizontalAlignment','center',...
              'FontSize',28,...
              'FontAngle','oblique',...
              'Color','b');
    h_inst = text (0,0,-0.95,'(Instructor Version)');
    set (h_inst,'HorizontalAlignment','center',...
              'FontSize',24,...
              'Color','r');
    
end