9 files changed, 67 insertions, 0 deletions
diff --git a/67/CH4/EX4.1/example41.sce b/67/CH4/EX4.1/example41.sce
new file mode 100755
index 000000000..114edcfa9
--- /dev/null
+++ b/67/CH4/EX4.1/example41.sce
@@ -0,0 +1,6 @@
+//Example 4.1
+//Find the DTFT of (a^n)u[n],for |a|<1
+clc;
+syms w a n;
+x=a^n;
+X=symsum(x*exp(-%i*w*n),n,0,%inf);
+\ No newline at end of file
diff --git a/67/CH4/EX4.10/example410.sce b/67/CH4/EX4.10/example410.sce
new file mode 100755
index 000000000..71c39fc42
--- /dev/null
+++ b/67/CH4/EX4.10/example410.sce
@@ -0,0 +1,9 @@
+//Example 4.10
+//Find DTFT of x[n]=cos(Won) with Wo=(2*pi/5)
+clc;
+syms w n;
+x1=exp(%i*(2*%pi*n/5));
+x2=exp(-%i*(2*%pi*n/5));
+X1=symsum(x1*exp(-%i*w*n),n,0,%inf);
+X2=symsum(x2*exp(-%i*w*n),n,0,%inf);
+X=(X1+X2)/2;
+\ No newline at end of file
diff --git a/67/CH4/EX4.12/example412.sce b/67/CH4/EX4.12/example412.sce
new file mode 100755
index 000000000..ceddd6d2f
--- /dev/null
+++ b/67/CH4/EX4.12/example412.sce
@@ -0,0 +1,6 @@
+//Example 4.12
+//Find DTFT of x[n]=u[n]
+clc;
+syms w n;
+x=1;
+X=symsum(x*exp(-%i*w*n),n,0,%inf);
+\ No newline at end of file
diff --git a/67/CH4/EX4.16/example416.sce b/67/CH4/EX4.16/example416.sce
new file mode 100755
index 000000000..ede67c797
--- /dev/null
+++ b/67/CH4/EX4.16/example416.sce
@@ -0,0 +1,6 @@
+//Example 4.16
+//Find DTFT of x[n]=(a^n)u[n],for 0<a<1
+clc;
+syms w a n;
+x=a^n;
+X=symsum(x*exp(-%i*w*n),n,0,%inf);
+\ No newline at end of file
diff --git a/67/CH4/EX4.2/example42.sce b/67/CH4/EX4.2/example42.sce
new file mode 100755
index 000000000..a71bf5e84
--- /dev/null
+++ b/67/CH4/EX4.2/example42.sce
@@ -0,0 +1,6 @@
+//Example 4.2
+//Find DTFT of x[n]=(a^n)u[-(n+1)]
+clc;
+syms w a n;
+x=a^n;
+X=symsum(x*exp(-%i*w*n),n,-%inf,-1);
+\ No newline at end of file
diff --git a/67/CH4/EX4.22/example422.sce b/67/CH4/EX4.22/example422.sce
new file mode 100755
index 000000000..32f85afd2
--- /dev/null
+++ b/67/CH4/EX4.22/example422.sce
@@ -0,0 +1,6 @@
+//Example 4.22
+//Find DTFT of x[n]=((1/2)^(n-1))u[n-1]
+clc;
+syms w n;
+x=(1/2)^(n-1);
+X=symsum(x*exp(-%i*w*n),n,1,%inf);
+\ No newline at end of file
diff --git a/67/CH4/EX4.3/example43.sce b/67/CH4/EX4.3/example43.sce
new file mode 100755
index 000000000..06dbbdf17
--- /dev/null
+++ b/67/CH4/EX4.3/example43.sce
@@ -0,0 +1,6 @@
+//Example 4.3
+//Find DTFT of unit impluse
+clc;
+syms w n;
+x=1;
+X=symsum(x*exp(-%i*w*n),n,0,0);
+\ No newline at end of file
diff --git a/67/CH4/EX4.5/example45.sce b/67/CH4/EX4.5/example45.sce
new file mode 100755
index 000000000..cb74a3fbc
--- /dev/null
+++ b/67/CH4/EX4.5/example45.sce
@@ -0,0 +1,10 @@
+//Example 4.5
+//Find DTFT of x[n]=a^|n| for -1<a<1
+clc;
+syms w a n;
+x1=a^n;
+x2=a^(-n);
+X1=symsum(x1*exp(-%i*w*n),n,0,%inf);
+X2=symsum(x2*exp(-%i*w*n),n,-%inf,-1);
+X=X1+X2;
+disp(X,'X(e^jw)=');
+\ No newline at end of file
diff --git a/67/CH4/EX4.9/example49.sce b/67/CH4/EX4.9/example49.sce
new file mode 100755
index 000000000..fd4317be9
--- /dev/null
+++ b/67/CH4/EX4.9/example49.sce
@@ -0,0 +1,12 @@
+//Example 4.9
+clc;
+syms w a n;
+x=a^n;
+pi=22/7;
+X=symsum(x*exp(-%i*w*n),n,0,%inf);
+n1=0:10;
+a=0.5;
+x1=a^n1;
+plot2d3(n1,x1);
+xtitle('Discrete Time Signal','n','x[n]');
+a.thickness=2;
+\ No newline at end of file