# Two Matrix array elements addition except the very first one

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altaf ahmed on 28 Apr 2019
I have a matrix of 10x10000 and want to add previous column with current one excpoet the very first one like below:
First Row contents are suppose: a1 a2 a3 a4 .....
After Addition operation, new matrix result as: a1 a2+a1 a3+a2 a4+a3 .......
So a1 reamins a1. All other subsequent are added to prevoius column values for all rows in a series.
Sample non-working code that I generated is below:
N = 10; % 10 terminals in the TDMA system
TOTAL_SERVED_PACKETS = 100000;
num_arrivals = TOTAL_SERVED_PACKETS/N;
interarrival_time = exprnd(mean_interarrival, N, num_arrivals);
for arrival_loop = 2:num_arrivals %iterate through Interaarival time array for each station
for station_num = 1:N %iterate through the arrays for all stations
offset = 1;
arrival_list = interarrival_time(station_num,arrival_loop-offset)+interarrival_time(station_num,arrival_loop);
offset = offset + 1;
arrival_loop = arrival_loop + 1;
if station_num == N
end
if arrival_loop == num_arrivals
end
end
end
I am getting this error: Index in position 2 exceeds array bounds (must not exceed 10000).

Prasanna Venkateshan on 7 Jul 2020
matrix=[1 2 3 4;5 6 7 8;9 10 11 12];
for i=1:size(matrix,1)
for j=size(matrix,2):-1:2
matrix(i,j)=matrix(i,j)+matrix(i,j-1);
end
end
disp(matrix)

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