Algebraic operation on the missing values

Hi

see
?complete.cases and/or ?is.na for evaluating non missing entries. 

However in any operation in which you use NA value, result shall be 
NA as you do not know what actually is NA.

HTH
Petr

Hi all,

I have a large set of descriptors, which are stored as the vectors,
each one containing about 450 elements. Now I have to perform some
algebraical operations on this set to eliminate the redundant ones.
The problem is, that not all vales in the vectors are known. Are there
any norm defined how should I process such vectors? Simple example:
having two vectors:

a      b
3      4
2      null
3      6

I can imagine that a+b is [7 null 9]', but what about scalar product?
Is it null or have it a value? I don't want to replace missing values
with the concrete ones, but they significantly complicate my
computations. 

Does anyone know whether there are any ways to solve this problem?
Please share some experience. Really appreciate the help!

Sincerely,

Joanna

Petr Pikal
petr.pikal at precheza.cz