load('a40001m.mat');
ABP = val;
FIVE_MIN = 37500; % samp_rate * 5min * 60sec/min -- should be an input in function
num5MinSegments = 1;  % 1-based, not 0-based
for num5MinSegments=1:length(ABP)/FIVE_MIN
   sumVal(num5MinSegments) = sum(ABP(1+FIVE_MIN*(num5MinSegments-1):FIVE_MIN+FIVE_MIN*(num5MinSegments-1)));
%    disp(1+37500*(num5MinSegments-1));
%    disp(37500+37500*(num5MinSegments-1));
end