how to find average value up to current row in Matrix

I have a matrix A

A =

[ 128 8.4

127 8.7

128 8.3 ]

I want to find average using A(1,1) * A(1,2)/sum(A(1,1)) for first row. And subsequently for next rows considering calculation of previous row.. And I need the values

B = [

128 8.4

255 8.549

383 8.466 ]

Please help me.

Answer 1

[Bruno Luong]

A =      [  128          8.4
    127          8.7
    128          8.3 ]

A = 3×2

128.0000 8.4000 127.0000 8.7000 128.0000 8.3000

A1 = A(:,1);
cs1 = cumsum(A1);
B = [cs1, cumsum(A1.*A(:,2))./cs1]

B = 3×2

128.0000 8.4000 255.0000 8.5494 383.0000 8.4661

[Triveni]

B = [cumsum(A(:,1)), cumsum(A(:,1).*A(:,2))./cumsum(A(:,1))]