initial commit / add all books

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diff --git a/842/CH1/EX0.15/Example0_15.sce b/842/CH1/EX0.15/Example0_15.sce
new file mode 100755
index 000000000..4d018c34e
--- /dev/null
+++ b/842/CH1/EX0.15/Example0_15.sce
@@ -0,0 +1,15 @@
+//clear//

+//Example 1.5:To express sum of two complex exponentials

+//as a single sinusoid

+clear;

+clc;

+close;

+t =0:1/100:2*%pi;

+x1 = exp(sqrt(-1)*2*t);

+x2 = exp(sqrt(-1)*3*t);

+x = x1+x2;

+for i = 1:length(x)

+  X(i) = sqrt((real(x(i)).^2)+(imag(x(i)).^2));

+end

+plot(t,X);

+xtitle('Full wave rectified sinusoid','time t','Magnitude');

diff --git a/842/CH1/EX01.13/Example01_13b.sce b/842/CH1/EX01.13/Example01_13b.sce
new file mode 100755
index 000000000..846653d10
--- /dev/null
+++ b/842/CH1/EX01.13/Example01_13b.sce
@@ -0,0 +1,21 @@
+//clear//

+//Example 1.13(b):Determination of stability of a given system

+//Page 50

+//given system y(t) = exp(x(t))

+clear;

+clc;

+Maximum_Limit = 10;

+S = 0;

+for t = 0:Maximum_Limit-1

+  x(t+1)= -2^t;          //Input some bounded value

+  S = S+exp(x(t+1));

+end 

+if (S >Maximum_Limit)

+  disp('Eventhough input is bounded output is unbounded')

+  disp('The given system is unstable');

+  disp('S =');

+  S

+ else

+  disp('The given system is stable');

+  disp(S);

+end

diff --git a/842/CH1/EX1.1/Example1_1.sce b/842/CH1/EX1.1/Example1_1.sce
new file mode 100755
index 000000000..8026ecf5d
--- /dev/null
+++ b/842/CH1/EX1.1/Example1_1.sce
@@ -0,0 +1,44 @@
+//clear//

+//Example 1.1: Time Shifting

+//SIGNALS & SYSTEMS, Second Edition

+//V.OPPENHEIM, S.WILLSKY, S.HAMID NAMWAB

+//PHI, 2008 Edition

+//Page 10

+clear;

+clc;

+close;

+t = 0:1/100:1;

+for i = 1:length(t)

+  x(i) = 1 ;

+end

+for i = length(t)+1:2*length(t)

+  x(i) = 1-t(i-length(t));

+end

+t1 = 0:1/100:2;

+t2 = -1:1/100:1;

+//t3 = 0:1/100:4/3;

+//t4 = 0:1/length(t3):1;

+//Mid =ceil(length(t3)/2);

+//for i = 1:Mid

+//  x3(i) = 1 ;

+//end

+//for i = Mid+1:length(t3)

+//  x3(i) = 1-t4(i-Mid);

+//end

+figure

+a=gca();

+plot2d(t1,x(1:$-1)) 

+a.thickness=2;

+xtitle('The signal x(t)')

+figure

+a=gca();

+plot2d(t2,x(1:$-1))

+a.thickness=2;

+a.y_location = "middle";

+xtitle('The signal x(t+1)')

+figure

+a=gca();

+plot2d(t2,x($:-1:2))

+a.thickness=2; 

+a.y_location = "middle";

+xtitle('The signal x(-t+1)')

diff --git a/842/CH1/EX1.12/Example1_12.sce b/842/CH1/EX1.12/Example1_12.sce
new file mode 100755
index 000000000..7ba769fd7
--- /dev/null
+++ b/842/CH1/EX1.12/Example1_12.sce
@@ -0,0 +1,27 @@
+//clear//

+//Example 1.12:Classification of system:Causality property

+//Page 47

+//To check whether the given discrete system is a Causal System (or) Non-Causal System

+//Given discrete system y[n]= x[-n]

+clear;

+clc;

+x = [2,4,6,8,10,0,0,0,1];  //Assign some value to input

+n = -length(x)/2:length(x)/2;

+count = 0;

+mid = ceil(length(x)/2);

+y = zeros(1,length(x));

+y(mid+1:$) = x($:-1:mid+1);

+for n = -1:-1:-mid

+  y(n+1+mid) = x(-n);

+end

+for i = 1:length(x)

+  if (y(i)==x(i))

+    count = count+1;

+  end

+end 

+if (count==length(x))

+    disp('The given system is a causal system')

+else

+    disp('Since it depends on future input value')

+    disp('The given system is a non-causal system')

+end

diff --git a/842/CH1/EX1.13/Example1_13.sce b/842/CH1/EX1.13/Example1_13.sce
new file mode 100755
index 000000000..bb0ca7c5b
--- /dev/null
+++ b/842/CH1/EX1.13/Example1_13.sce
@@ -0,0 +1,22 @@
+//clear//

+//Example 1.13:Determination of stablility of a given system

+//Page 49

+//given system y(t) = t.x(t)

+clear;

+clc;

+x = [1,2,3,4,0,2,1,3,5,8]; //Assign some input 

+Maximum_Limit = 10;

+S = 0;

+for t = 0:Maximum_Limit-1

+  S = S+t*x(t+1);

+end 

+if (S >Maximum_Limit)

+  disp('Eventhough input is bounded output is unbounded')

+  disp('The given system is unstable');

+  disp('S =');

+  S

+ else

+  disp('The given system is stable');

+  disp('The value of S =');

+  S

+end

diff --git a/842/CH1/EX1.14/Example1_14.sce b/842/CH1/EX1.14/Example1_14.sce
new file mode 100755
index 000000000..01e5094b1
--- /dev/null
+++ b/842/CH1/EX1.14/Example1_14.sce
@@ -0,0 +1,21 @@
+//clear//

+//Example 1.14:classification of a system:Time Invariance Property

+//Page 51

+//To check whether the given system is a Time variant (or) Time In-variant

+// The given discrete signal is y(t) = sin(x(t))

+clear;

+clc;

+to = 2; //Assume the amount of time shift  =2

+T = 10; //Length of given  signal

+for t = 1:T

+  x(t) = (2*%pi/T)*t;

+  y(t) = sin(x(t));

+end

+//First shift the input signal only

+Input_shift = sin(x(T-to));

+Output_shift = y(T-to);

+if(Input_shift == Output_shift)

+  disp('The given discrete system is a Time In-variant system');

+else

+  disp('The given discrete system is a Time Variant system');

+end

diff --git a/842/CH1/EX1.15/Example1_15.sce b/842/CH1/EX1.15/Example1_15.sce
new file mode 100755
index 000000000..3fe295692
--- /dev/null
+++ b/842/CH1/EX1.15/Example1_15.sce
@@ -0,0 +1,21 @@
+//clear//

+//Example 1.15:Classification of a System:Time Invariance Property

+//Page 51

+//To check whether the given system is a Time variant (or) Time In-variant

+// The given discrete signal is y[n] = n.x[n]

+clear;

+clc;

+no = 2; //Assume the amount of time shift  =2

+L = 10; //Length of given  signal

+for n = 1:L

+  x(n) = n;

+  y(n) = n*x(n);

+end

+//First shift the input signal only

+Input_shift = x(L-no);

+Output_shift = y(L-no);

+if(Input_shift == Output_shift)

+  disp('The given discrete system is a Time In-variant system');

+else

+  disp('The given discrete system is a Time Variant system');

+end

diff --git a/842/CH1/EX1.16/Example1_16.sce b/842/CH1/EX1.16/Example1_16.sce
new file mode 100755
index 000000000..1fcbfd98d
--- /dev/null
+++ b/842/CH1/EX1.16/Example1_16.sce
@@ -0,0 +1,22 @@
+//clear//

+//Example 1.16:Classification of system:Time Invariance Property

+//Page 52

+//To check whether the given system is a Time variant (or) Time In-variant

+// The given discrete signal is y(t) = x(2t)

+clear;

+clc;

+to = 2; //Assume the amount of time shift  =2

+T = 10; //Length of given  signal

+x = [1,2,3,4,5,6,7,8,9,10];

+y = zeros(1,length(x));

+for t = 1:length(x)/2

+    y(t) = x(2*t);

+end

+//First shift the input signal only

+Input_shift = x(T-to);

+Output_shift = y(T-to);

+if(Input_shift == Output_shift)

+  disp('The given discrete system is a Time In-variant system');

+else

+  disp('The given discrete system is a Time Variant system');

+end

diff --git a/842/CH1/EX1.17/Example1_17.sce b/842/CH1/EX1.17/Example1_17.sce
new file mode 100755
index 000000000..7e40a63fe
--- /dev/null
+++ b/842/CH1/EX1.17/Example1_17.sce
@@ -0,0 +1,37 @@
+//clear//

+//Example 1.17:Classification of system:Linearity Property

+//Page 54

+//To check whether the given discrete system is a Linear System (or) Non-Linear System

+//Given discrete system y(t)= t*x(t)

+clear;

+clc;

+x1 = [1,1,1,1];

+x2 = [2,2,2,2];

+a = 1;

+b = 1;

+for t = 1:length(x1)

+  x3(t) = a*x1(t)+b*x2(t);

+end

+for t = 1:length(x1)

+  y1(t) = t*x1(t);

+  y2(t) = t*x2(t);

+  y3(t) = t*x3(t);

+end

+for t = 1:length(y1)

+  z(t) = a*y1(t)+b*y2(t);

+end

+count = 0;

+for n =1:length(y1)

+  if(y3(t)== z(t))

+    count = count+1;

+  end

+end

+if(count == length(y3))

+   disp('Since It satisifies the superposition principle')

+   disp('The given system is a Linear system')

+   y3

+   z

+  else

+    disp('Since It does not satisify the superposition principle')

+    disp('The given system is a Non-Linear system')

+end

diff --git a/842/CH1/EX1.18/Example1_18.sce b/842/CH1/EX1.18/Example1_18.sce
new file mode 100755
index 000000000..6b5e9e280
--- /dev/null
+++ b/842/CH1/EX1.18/Example1_18.sce
@@ -0,0 +1,37 @@
+//clear//

+//Example 1.18:Classsification of a system:Linearity Property

+//Page 54

+//To check whether the given discrete system is a Linear System (or) Non-Linear System

+//Given discrete system y(t)= (x(t)^2)

+clear;

+clc;

+x1 = [1,1,1,1];

+x2 = [2,2,2,2];

+a = 1;

+b = 1;

+for t = 1:length(x1)

+  x3(t) = a*x1(t)+b*x2(t);

+end

+for t = 1:length(x1)

+  y1(t) = (x1(t)^2);

+  y2(t) = (x2(t)^2);

+  y3(t) = (x3(t)^2);

+end

+for t = 1:length(y1)

+  z(t) = a*y1(t)+b*y2(t);

+end

+count = 0;

+for n =1:length(y1)

+  if(y3(t)== z(t))

+    count = count+1;

+  end

+end

+if(count == length(y3))

+   disp('Since It satisifies the superposition principle')

+   disp('The given system is a Linear system')

+   y3

+   z

+  else

+    disp('Since It does not satisify the superposition principle')

+    disp('The given system is a Non-Linear system')

+end

diff --git a/842/CH1/EX1.2/Example1_2.sce b/842/CH1/EX1.2/Example1_2.sce
new file mode 100755
index 000000000..597370f3d
--- /dev/null
+++ b/842/CH1/EX1.2/Example1_2.sce
@@ -0,0 +1,23 @@
+//clear//

+//Example 1.2:Time Scaling

+//SIGNALS & SYSTEMS, Second Edition

+//V.OPPENHEIM, S.WILLSKY, S.HAMID NAMWAB

+//PHI, 2008 Edition

+//Page 11

+clear;

+clc;

+close;

+t3 = 0:1/100:4/3;

+t4 = 0:1/length(t3):1;

+Mid =ceil(length(t3)/2);

+for i = 1:Mid

+  x3(i) = 1 ;

+end

+for i = Mid+1:length(t3)

+  x3(i) = 1-t4(i-Mid);

+end

+figure

+a=gca();

+plot2d(t3,x3) 

+a.thickness=2;

+xtitle('Time Scaling x(3t/2)')

diff --git a/842/CH1/EX1.20/Example1_20.sce b/842/CH1/EX1.20/Example1_20.sce
new file mode 100755
index 000000000..6ed3e4665
--- /dev/null
+++ b/842/CH1/EX1.20/Example1_20.sce
@@ -0,0 +1,37 @@
+//clear//

+//Example 1.20:Classsification of a system:Linearity Property

+//Page 55

+//To check whether the given discrete system is a Linear System (or) Non-Linear System

+//Given discrete system y[n])= 2*x[n]+3

+clear;

+clc;

+x1 = [1,1,1,1];

+x2 = [2,2,2,2];

+a = 1;

+b = 1;

+for n = 1:length(x1)

+  x3(n) = a*x1(n)+b*x2(n);

+end

+for n = 1:length(x1)

+  y1(n) = 2*x1(n)+3;

+  y2(n) = 2*x2(n)+3;

+  y3(n) = 2*x3(n)+3;

+end

+for n = 1:length(y1)

+  z(n) = a*y1(n)+b*y2(n);

+end

+count = 0;

+for n =1:length(y1)

+  if(y3(n)== z(n))

+    count = count+1;

+  end

+end

+if(count == length(y3))

+   disp('Since It satisifies the superposition principle')

+   disp('The given system is a Linear system')

+   y3

+   z

+  else

+    disp('Since It does not satisify the superposition principle')

+    disp('The given system is a Non-Linear system')

+end

diff --git a/842/CH1/EX1.3/Example1_3.sce b/842/CH1/EX1.3/Example1_3.sce
new file mode 100755
index 000000000..41e4f2592
--- /dev/null
+++ b/842/CH1/EX1.3/Example1_3.sce
@@ -0,0 +1,25 @@
+//clear//

+//Example 1.3:Time Scaling and Time Shifting

+//SIGNALS & SYSTEMS, Second Edition

+//V.OPPENHEIM, S.WILLSKY, S.HAMID NAMWAB

+//PHI, 2008 Edition

+//Page 11

+clear;

+clc;

+close;

+t3 = 0:1/100:4/3;

+t4 = 0:1/length(t3):1;

+Mid =ceil(length(t3)/2);

+for i = 1:Mid

+  x3(i) = 1 ;

+end

+for i = Mid+1:length(t3)

+  x3(i) = 1-t4(i-Mid);

+end

+t5 = -2/3:1/100:2/3;

+figure

+a=gca();

+plot2d(t5,x3) 

+a.thickness=2;

+a.y_location ="middle";

+xtitle('Time Scaling and Time Shifting x((3t/2)+1)')

diff --git a/842/CH1/EX1.4/Example1_4.sce b/842/CH1/EX1.4/Example1_4.sce
new file mode 100755
index 000000000..0dcff04d1
--- /dev/null
+++ b/842/CH1/EX1.4/Example1_4.sce
@@ -0,0 +1,18 @@
+//clear//

+//Example 1.4:Combinationation two periodic signals

+// Aperiodic signal

+//Page 12

+clear;

+clc;

+close;

+F=1;  //Frequency  = 1 Hz

+t1 = 0:-1/100:-2*%pi; 

+x1 = cos(F*t1);

+t2 = 0:1/100:2*%pi;

+x2 = sin(F*t2);

+a=gca();

+plot(t2,x2);

+plot(t1,x1);

+a.y_location = "middle";

+a.x_location = "middle";

+xtitle('The signal x(t) = cost for t < 0 and sint for t > 0: Aperiodic Signal')

diff --git a/842/CH1/EX1.6/Example1_6.sce b/842/CH1/EX1.6/Example1_6.sce
new file mode 100755
index 000000000..a539fee43
--- /dev/null
+++ b/842/CH1/EX1.6/Example1_6.sce
@@ -0,0 +1,33 @@
+//clear//

+//Example 1.6:Determine the fundamental period of composite

+// discrete time signal

+//x[n] = exp(j(2*%pi/3)n)+exp(j(3*%pi/4)n)

+clear;

+clc;

+close;

+Omega1 = 2*%pi/3;   //Angular frequency signal 1

+Omega2 = 3*%pi/4;  //Angular frequency signal 2

+N1 = (2*%pi)/Omega1;  //Peirod of signal 1

+N2 = (2*%pi)/Omega2;  //Period of signal 2

+//To find rational period of signal 1

+for m1 = 1:100

+  period = N1*m1;

+  if(modulo(period,1)==0)

+    period1 = period;

+    integer_value = m1

+    break;

+  end

+end

+//To find rational period of signal 2

+for m2 = 1:100

+  period = N2*m2;

+  if(modulo(period,1)==0)

+    period2 = period;

+    integer_value = m2

+    break;

+  end

+end

+disp(period1)

+disp(period2)

+//To determine the fundamental period N

+N = period1*period2