Stepping over / removing duplicate points

If I want to populate B with derived values from Matrix A using the following specifiers how could I do this?

Point 1 = 800 (A(1,1))

I then want to populate the B matrix (1,1) with the first point 2 value.

The observation equation would be B(1,1) = A(1,1) + A(1,3)

I then want to run through the B matrix using that elements value + the corresponding element in A(:,3), ie the B matrix element position to look for the same value throughout A. See further down for further explanation.

Counter_1 = 1
Counter_2=1
Row_count = 1
m = 1
To_specifier = 1
Delete_count =1
Del_from_B =1
Val = 1

    for Counter_1 = 1:7

    for Counter_2 = 1:10

    if A(Row_count,2) == Val

    B(To_specifier ,1) = A(1,1) + A(Row_count,4)

    s=s+1

    A(Row_count,2) = 0 % used to show what code is doing throughout breakpoints.

    else if A(Row_count,2) == Val +1 % point #2

    B(A(Row_count,3) = B(s-1,1) + A(Row_count,4)

A(Row_count,2) = 0

end

val = val+1 % want to then peruse the next point value in increasing sequence.

I want to also put a subroutine in the code so that if there is a value in element B that element number (position of element and not value inside it), will be removed from all of the A(:,3) thus removing any duplicate calculations for that point.

A=
  800  1  2  4.3    
    NaN  2  4  3.6    
    NaN  3  6  2.1    
    NaN  4  3  4.8    
    NaN  5  7  11.1    
    NaN  6  3  -12    
    NaN  6  5  -4    
    NaN  1  4  -17    
    NaN  2  5  -15    
    NaN  3  6  -7      

B = zeros (1:6)