written 8.4 years ago by | • modified 8.4 years ago |
Letter | Probability | CDF |
---|---|---|
w | 0.15 | 0.15 |
x | 0.1 | 0.25 |
y | 0.7 | 0.95 |
z | 0.05 | 1 |
Range: w (0, 0.15) x (0.15, 0.25)
y (0.25, 0.95) z (0.95, 1)
Formulae: $l_n = l_{n-1} + ( U_{n-1} – l_{n-1} ) F_n-1 (x)$
$U_n= l_{n-1} + ( U_{n-1} – l_{n-1} ) F_n (x)$
a) Initially $U_0 = 1 \ and \ l_0 =0$
i. For x:
$l_n$ = 0+ (1-0) × 0.15 =0.15
$U_n$ = 0 + (1-0) × 0.25 = 0.25
Tag for x = ( 0.15, 0.25)
ii. Tag for y:
$l_n$ = 0.15 + (0.25 – 0.15 ) × 0.25 = 0.175
$U_n$ = 0.245
Tag for xy = (0.175, 0.245)
iii. Tag for z
$l_n$ = 0.175 + (0.245 – 0.175) × 0.75 = 0.2415
$U_n$ = 0.175 + (0.245 – 0.175) × 1 = 0.245
Tag for xyz = (0.245 , 0.245)
iv. Tag for w
$l_n$ = 0.2415 + (0.245 – 0.2415) × 0 = 0.2415
$U_n$ = 0.2415 + (0.245 – 0.2415) × 0.15 = 0.242025
Tag for xyzw = (0.242025 , 0.2415)
v. Tag for z
$l_n$ = 0.2415 + ( 0.242025 – 0.2415) × 0.9 = 0.24199875
$U_n$ = 0.2415 + (0.242025 – 0.2415 ) × 1 = 0.242025
Tag for xyzwz = (0.24199875, 0.242025)
Tag generated for the sequence =
Tag generated for the sequence xyzwz = = 0.242011875
b) Deciphering the tag
Tag obtained = 0.242011845
Range of Symbols :
w (0, 0.15) x (0.15, 0.25)
y (0.25, 0.95) z ( 0.95, 1)
New tag (T ’ ) =
i. Tag obtained lies in range of x
First decoded symbol = ‘x’
T = = 0.9201
ii. Tag obtained lies in range of y
Next Symbol = ‘y’
T = = 0.9573
iii. Tag obtained lies in range of z
Next Symbol = ‘z’
T = = 0.1463
iv. Tag generated lies in range of w
Next Symbol = ‘w’
T ‘ = = 0.975
v. Tag generated lies in the range of z
Next Symbol ‘Z’
T ‘ = = 0.5
Generating sequence till symbols we get the sequence xyzwz