"Convolution" Calculation Method

How to Caculate “Convolution”:
If give you a matrix as “A”,such as:

3   0   1   21   5   8   92   7   2   50   1   3   1

Another matrix as “B”,such as:

1   0   -11   0   -11   0   -1

Symbol “ * ” is “Convolution”
So matrix “C”:
C = A * B
Method:

3x1 0x0 1x(-1)  21x1 5x0 8x(-1)  92x1 7x0 2x(-1)  50   1   3       1

The “Caculated” numbers correspond the “(HERE)” POSITION in “C”:

(HERE)  (other)(other) (other)

So the same as this way(next is moving to right ONE bit),calculate others’ position.
PS:
A(axa) * B(bxb) = C([c=a-b+1]x[c=a-b+1])