multiplication of two array in a particular way

[Rahul]

i have 4 different numbers in two columns say A & B. i want to
multiply them & get the result in column C, multiplication should be
done in the following manner:-

C1= A1*B1
C2= A2*B1+B2*A1
C3= A1*B3+A2*B2+A3*B1
C4= A1*B4+A2*B3+A3*B2+A4*B1

can you please help me in this?

 

[Pete_UK]

I don't see what your problem is - can't you just put those formulae
in the cells stated and then you have what you wanted?

Pete

 

[Mike H]

Hi,

Unlike your previous question where there was a logical order for the
summing this appears random and while I hope someone provides a solution, I'm
a bit doubtful it can be done in a single formula. I suggest you enter those
formulas as you describe.

Mike