Plotting a specific part of the array

I have a problem with plotting a specific part of the array. I have 3 arrays x(1,n), y1(1,n) and y2(1,n). Values in arrays y1 and y2 initially have the same value then they starting to differ to finally have the same value. A simple example is:

x1= 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14 , 15,

y1 = 4.5, 5, 5.5, 6, 7, 8, 9, 8, 7, 7, 6, 5.5, 5, 5, 4.5,

y2 = 4.5, 5, 5.5, 4, 3, 2, 1, 1, 2, 3, 4, 5.5, 5, 5, 4.5,

I would like to use the figure function but limit the input size to the only part where they differ so:

x1= 4, 5, 6, 7, 8, 9, 10, 11

y1 = 6, 7, 8, 9, 8, 7, 7, 6,

y2 = 4, 3, 2, 1, 1, 2, 3, 4,

I will apreciate any help or hint.

Answer 1

[KALYAN ACHARJYA]

idy1=y1(y1~=y2)
idy2=y2(y2~=y1)

Results:

idy1 =
     6     7     8     9     8     7     7     6
idy2 =
     4     3     2     1     1     2     3     4

Note: x1 having length 14, whereas y1 and y2 having length 15, Now x1 comparision with?