Sinusoids - DSP Using MATLAB and Wavelets - page 151

smooth4 = Xmag(5)*cos(2*pi*4*t/Xsize + Xphase(5))/Xsize;
smooth5 = Xmag(6)*cos(2*pi*5*t/Xsize + Xphase(6))/Xsize;
smooth6 = Xmag(7)*cos(2*pi*6*t/Xsize + Xphase(7))/Xsize;
smooth7 = Xmag(8)*cos(2*pi*7*t/Xsize + Xphase(8))/Xsize;
% Find the IFFT (the hard way) part 2
my_sum_of_sins = (s0+s1+s2+s3+s4+s5+s6+s7);
smooth_sum = smooth0 + smooth1 + smooth2 + smooth3;
smooth_sum = smooth_sum + smooth4 + smooth5 + smooth6 + smooth7;
% Show both discrete points and smooth curves together
xaxis1 = (0:length(smooth0)-1)/20; % for 8 points
xaxis2 = (0:length(s0)-1);
figure(1);
subplot(4,1,1); plot(xaxis1, smooth0, g, xaxis2, s0, r*);
subplot(4,1,2); plot(xaxis1, smooth1, g, xaxis2, s1, r*);
subplot(4,1,3); plot(xaxis1, smooth2, g, xaxis2, s2, r*);
subplot(4,1,4); plot(xaxis1, smooth3, g, xaxis2, s3, r*);
ylabel(amplitude);
xlabel(sample);
figure(2);
subplot(4,1,1); plot(xaxis1, smooth4, g, xaxis2, s4, r*);
subplot(4,1,2); plot(xaxis1, smooth5, g, xaxis2, s5, r*);
subplot(4,1,3); plot(xaxis1, smooth6, g, xaxis2, s6, r*);
subplot(4,1,4); plot(xaxis1, smooth7, g, xaxis2, s7, r*);
ylabel(amplitude);
xlabel(sample);
% Show the original versus the reconstruction from freq-domain
figure(3);
subplot(2,1,1); plot(0:Xsize-1, x, bd);
title(original);
min_y = floor(min(smooth_sum));
max_y = ceil(max(smooth_sum));
axis([0, Xsize-1, min_y, max_y]); % Make the axes look nice
xaxis1 = (0:length(smooth_sum)-1)/20;
xaxis2 = (0:length(s0)-1);
subplot(2,1,2);