initial commit / add all books

1 files changed, 42 insertions, 0 deletions

diff --git a/40/CH8/EX8.5a/Exa_8_5a.sce b/40/CH8/EX8.5a/Exa_8_5a.sce
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+//properties of DFT

+//a1)product

+xn=[1 2 1 0];

+XDFT=dft(xn,-1)

+hn=xn.*xn

+HDFT=dft(hn,-1)

+HDFT1=1/4*(convol(XDFT,XDFT))

+HDFT1=[HDFT1,zeros(8:12)];

+HDFT2=[HDFT1(1:4);HDFT1(5:8);HDFT1(9:12)];

+HDFT3=[0 0 0 0];

+for i=1:4

+    for j=1:3

+        HDFT3(i)=HDFT3(i)+HDFT2(j,i);

+    end

+end

+disp(HDFT3,'DFT of x[n]^2 is');

+//a2)periodic convolution

+vn=convol(xn,xn);

+vn=[vn,zeros(8:12)];

+vn=[vn(1:4);vn(5:8);vn(9:12)];

+vn1=[0 0 0 0];

+for i=1:4

+    for j=1:3

+        vn1(i)=vn1(i)+vn(j,i);

+    end

+end

+VDFT=dft(vn1,-1);

+VDFT1=XDFT.*XDFT;

+disp(VDFT1,'DFT of x[n]*x[n] is');

+//a3)signal energy(parcewell's theorem)

+xn2=xn^2;

+E=0;

+for i=1:length(xn2)

+    E=E+abs(xn2(i));

+end

+XDFT2=XDFT^2

+E1=0;

+for i=1:length(XDFT2)

+    E1=E1+abs(XDFT2(i));

+end

+E,(1/4)*E1;

+disp(1/4*E1,'The energy of the signal is');
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