I am trying to find the area as a part of a graph(Area-A and Area-B in the picture below). However, when I am using "trapz" function, it is not giving any output. Code is mentioned below and .mat file is attached. Please help me out.

clc;
a=importdata('anirban normal.mat');
b=a.data;
x=b(22810:25750,1);
figure();
plot(x);
Area=trapz(1:694);
x(x<0)=[];
findpeaks(x);
findpeaks(x,'MinPeakHeight',0.927);*

[KSSV]

.mat file is missing...

[Biswarup Dutta]

I have added the .mat file.

Answer 1

[KSSV]

a=importdata('anirban normal.mat');
b=a.data;
x=b(22810:25750,1);
figure();
plot(x);
% Area=trapz(1:694);

id = 1:length(x) ;
% Int = trapz(id,x) ;
% x(x<0)=[];
% findpeaks(x);
% findpeaks(x,'MinPeakHeight',0.927);
[val,maxid] = max(x) ;

Area1 = trapz(id(1:maxid),x(1:maxid)) ;
Area2 = trapz(id(maxid:end),x(maxid:end)) ;
Area =  trapz(id,x) ;

Check Area = Area1+Area2

[Biswarup Dutta]

Hello KSSV, I have tried the code suggested by you but it's not giving me the area. The output is shown in the picture.

[KSSV]

It is Area1 and Area2 not Area_1, Area_2.

[Biswarup Dutta]

Hello KSSV, area is derived. Thanks for your help. Is there any way to select Area 1 and Area 2, paint it with different colors using matlab code. I have tried something like that but it does not work:

clc
a=importdata('robin roy.mat');
b=a.data;
x=b(22000:25830,1);
plot(x);
x(x<0)=[];
findpeaks(x);
findpeaks(x,'MinPeakHeight',1.15);
Area1 = trapz(id(1:447),x(1:447)) ;
Area2 = trapz(id(447:1815),x(447:1815)) ;
hold on
ha1 = area(x(x<=447), y(x<=447), 'FaceColor','g');
ha2 = area([447  x0], [y(x == 447) 0], 'FaceColor','r');
hold off
A1str = sprintf('Area 1 = %6.3f', Area1);
A2str = sprintf('Area 2 = %6.3f', Area2);
legend([ha1 ha2], A1str, A2str)

I have uploaded the .mat file. The graph is similar to above one, I have attached.