Intro: fairly new to matlab coming from mathematica environment.
Question: I have to calculate based on (x,y) 2D data and plot the same with the answer from the calculation shown on every plot. Assuming I have 10 2D arrays that needs to a FWHM calculation and the FWHM answer written to all of them and saved.
Code below for FWHM function:
function width = fwhm(x,y)% Define function for FWHM at 50%
y = y / max(y); % Normalize to 1 so that half max=0.5
N = length(y); % Max length of Y
MicroscopeMag=10; % Magnification of objective
PixelWidth=7.8; % Pixel Pitch is 7.8 Microns - Hamamatsu.
%------- identifies the centre of the peak ---------------%
[~,centerindex] = max(y);% Find center peak and coordinate
%------- Identifies the last index position before half-maximum ------%
%----- Have a range containing the leading edge of the signal -----%
i = 2; while sign(y(i)-0.5) == sign(y(i-1)-0.5) %trying to see the curve raise
i = i+1; end %-----Interpolate the exact point(s) where the signal's value would be 0.5-----%
%----- The next 2 lines are an attempt to determine in fractions of an
%Index exactly where the line would cross the 0.5 value.
%Simple linear interpolation -----%
interp = (0.5-y(i-1)) / (y(i)-y(i-1)); %(gives us the delta_y between the two values either side)/(shortfall)
%=linearly interpolate how far between the two index positions we should go to hit exactly 0.5
tlead = x(i-1) + interp*(x(i)-x(i-1)); % Works out the corresponding delta_x, which gives you the actual distance in terms of the timebase.
i=centerindex+1; %------- start search for next crossing at center--------------------%
%------- Repeat process for trailing edge --------------------%
while ((sign(y(i)-0.5) == sign(y(i-1)-0.5)) && (i <= N-1)) i = i+1; end if i ~= N interp = (0.5-y(i-1)) / (y(i)-y(i-1)); ttrail = x(i-1) + interp*(x(i)-x(i-1)); % Lateral Magnification x Pixel pitch of 7.8 microns.
width=((ttrail - tlead)/MicroscopeMag)*PixelWidth; end
Code to calculate the FWHM for every 2D array
clear all; a=1; while a<=10; filename=strcat('S',num2str(a),'.csv'); Array=csvread(filename,15,0); x = Array(:, 1); y = Array(:, 2); fwhm(x,y) a = a+1; end
The 10 files are in the zip attached here.
Best Answer