MATLAB: Area under the curve with conditions

integrationline

I want to do following tasks,
First generate a time series load data between 550-1000 for one day 30 min interval, so is load(48*1) dataset
then set level_1 = 750 and draw a line on the graph,
then find out the area above this level_1 line and area under seprate level (lets say level_2 = 600) line seprately

Best Answer

Try this: 
t = 1:48;                                                   % Time Vector
load = randi(1000, 1, 48);                                  % Create Data
level_1 = 750;
level_2 = 600;
above_level_1 = load >= level_1;                            % Logical Index Vector

area_1 = trapz(t(above_level_1), load(above_level_1));      % Area Under ‘Level_1’
below_level_2 = load <= level_2;                            % Logical Index Vector
area_2 = trapz(t(below_level_2), load(below_level_2));      % Area Under ‘Level_2’
figure
plot(t, load)
hold on
plot(xlim, [1 1]*level_1)
plot(xlim, [1 1]*level_2)
hold off
grid
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