This is going to be a long post due to information that I am going to have to present.
A brief outline in what I am asking is, that I need to integrate a Gaussian at a specific height above the x-axis so I don't want all the integration just a certain part under the curve. I have written the code to which I believe is integration all the values under the curve which I dont not want.
Here all data and full explanation with code.
So my lab experiment is on gamma ray spectroscopy and I need to find the amount of counts underneath the curve, now this was done on a program called cassy, where we could highlight the area and it would calculate this or us, but due to a miss hap one of the data plot was not integrated correctly so I am trying to do it on matab.
Starting with a count I have already integrated and a total count of $529$ for I will use this as an example.
Actual graph of data/code
The red portion is what I am trying to integrate.
Matlab code:
dataset = xlsread('Lab 3 Results 11.10.18 (1).xlsx','Sheet3','C4:D515');
x=dataset(:,1);
y=dataset(:,2);
plot(x,y)
So because of the random decay pattern of the sample, I extracted the data or that photo peak from the excel and fitted a Gaussian function to it using the curve fitting tool in matlab, like so.
Data Fit For Gaussian: I cherry picked the data for that peak from the raw data
From here I took the coefficient an set up the matlab code to produce just this Gaussian fit.
Code dataset = xlsread('Lab 3 Results 11.10.18 (1).xlsx','Sheet3','C394:D427');
x=dataset(:,1);
a1=38.51;
b1=1179;
c1=36.51;
y=a1*exp(-((x-b1)/c1).^2);
plot(x,y)
The part in green is not what I want and the part in read is, below is the code for what I belive is the total area or the read and green, i just not sure how to remove the green portion so I can get the data just for the red.
Code For numerical integration
dataset = xlsread('Lab 3 Results 11.10.18 (1).xlsx','Sheet3','C394:D427');
x=dataset(:,1);
a1=38.51;
b1=1179;
c1=36.51;
y=a1*exp(-((x-b1)/c1).^2);
int=trapz(y)
this code give int=$783.5391$ which is not far off the $529$ done by the cassy program, and my thought are that the my code is integrating the red and green area not just the red, but I am very new to matalb and not really sure what parameters are needed to get it to integrate just the red area.
Is there some advice someone could give