Formula for this summation expression

hoopeht

New Member
Joined
Feb 16, 2016
Messages
3
Trying to calculate this in vba: a(), b(), and c() are all arrays whose indexes go from 1 to 10. I know the values of array a and b. I need to calculate values of array c. The values are calculated as following:

c(1) = a(1) * b(1)
c(2) = a(1) * b(2) + a(2) * b(1)
c(3) = a(1) * b(3) + a(2) * b(2) + a(3) * b(1)
...
c(10) = a(1) * b(10) + a(2) * b(9) +...+ a(9) * b(2) + a(10) * b(1)

Instead of writing out the ten equations one by one, is there an easier way to do this?
 

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Using Function Arguments with nested formulas
If writing INDEX in Func. Arguments, type MATCH(. Use the mouse to click inside MATCH in the formula bar. Dialog switches to MATCH.

Richard U

Active Member
Joined
Feb 14, 2006
Messages
399
Office Version
  1. 365
  2. 2016
  3. 2010
  4. 2007
Platform
  1. Windows
You'd probably want to do it the way you are doing it.

From a maintenance standpoint, it's easier. "Simplifying" it would probably involve the evaluate function and a formula that would be complex enough to require more comments reminding yourself what you did than would be worth it.

I'm a big fan of explicit coding though.
 

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