# Fitting a curve to a histogram

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ka chun yick on 13 Feb 2020
Edited: ka chun yick on 14 Feb 2020
Hi,
This is my current script. I would like to fit a curve to a histogram as shown in the picture below: What lines should i add to the existing script?
yA = randn(1000,1)*7+15;
yB = randn(1000,1)*3+7;
yC = randn(1000,1)*4+30;
% specify number of bins and edges of those bins; this example evenly spaces bins
NumBins = 25;
BinEdges = linspace(0,50,25);
% use histcounts and specify your bins
cntA = histcounts(yA,'BinEdges',BinEdges);
cntB = histcounts(yB,'BinEdges',BinEdges);
cntC = histcounts(yC,'BinEdges',BinEdges);
% plot
figure(1); cla; hold on;
% convert bin edges into bin centers
b = BinEdges(1:end-1)+diff(BinEdges)/2
% use bar
bar(b,[cntA',cntB',cntC'],'stacked')

KALYAN ACHARJYA on 13 Feb 2020
data=[yA;yB;yC]
histfit(data)

ka chun yick on 14 Feb 2020
Edited: ka chun yick on 14 Feb 2020
Hi,
I added these two lines, but the plot seems not correct..... I tried
% specify number of bins and edges of those bins; this example evenly spaces bins
NumBins = 100;
BinEdges = linspace(0,35,70);
% use histcounts and specify your bins
cntA = histcounts(yA,'BinEdges',BinEdges);
cntB = histcounts(yB,'BinEdges',BinEdges);
cntC = histcounts(yC,'BinEdges',BinEdges);
% plot
figure(1); cla; hold on;
data=[yA;yB;yC]
histfit(data)
% convert bin edges into bin centers
b = BinEdges(1:end-1)+diff(BinEdges)/2
% use bar
bar(b,[cntA',cntB',cntC'],'stacked')
% Labels
xlabel('Length of single walled carbon nanotubes (mm)')
ylabel('Count of CNT(log scale)')
set(gca,'YScale','log')
legend({'30(mins)', '120(mins)', '240(mins)'})
title('Count of CNT against length of SWCNTs in -0.67 degree(log scale)')