Arrays

[molla]

How can I access only one value of a column in array or suppose

X  Y

2   1

2   5

3   6

 I need output as

X Y  Z

2  1  2

2  5 10

3  6  12

Multiplying value 1 of x with all values of y 

How it is done using array

[Reeza]

That wouldn't use an array at all. Arrays are short cut references to variables and work only on a single row.

A SAS data step loops through all rows implicitly.

data want_mult;
set have;

Z = x * y;

run;

EDIT: I misunderstood your question so this answer is incorrect, but I'm leaving it rather than deleting since it's already out there. 

[Astounding · Accepted solution]

Arrays are not part of the solution.  Arrays always refer to a single observation at a time. 

Here is a way to get what you are asking for:

data want;

set have;

if _n_=1 then first_x = x;

retain first_x;

z = first_x * y;

drop first_x;

run;