Documentation/How Tos/Calc: SUMPRODUCT function
From Apache OpenOffice Wiki
SUMPRODUCT
Multiplies corresponding elements in the given ranges, and returns the sum of those products.
Syntax:
SUMPRODUCT(range1; range2; ... range30)
range1 to range30 are up to 30 ranges whose corresponding elements are to be multiplied.
You can use SUMPRODUCT to calculate the scalar product of two vectors.
SUMPRODUCT can also be used to sum cells where a specified condition is true - see Conditional Counting and Summation.
Example:
=SUMPRODUCT(A1:B3; C1:D3)
- returns A1*C1 + B1*D1 + A2*C2 + B2*D2 + A3*C3 + B3*D3