finding peak start and end points - matlab

Question

I have a series of peaks Peaks image, I used matlab findpeaks to find the peak points .
I need to find peak widths and the peak start and end points ? I have started
with this code , but it is not giving me the right width calculation :
% If the peak is at index 150
% Scan to the right.
for k = 151:length(signal)
if signal(k) < signal(k-1)
% Signal is starting to fall.
rightIndex = k-1;
break;
end
end
% Scan to the left.
for k = 149: -1 : 1
if signal(k) < signal(k+1)
% Signal is starting to fall.
leftIndex = k+1;
break;
end
end
peakWidth = rightIndex - leftIndex;

Answer 1

here there are two kinds of widths, on computed by findpeaks and one computed naively by comparing derivative to zero:
% generate sinal
x = 0:0.1:10;
y = x.*sin(x/5).*sin(5*x.^2);
% get derivatives
dy = diff(y);
dx = diff(x);
dy_dx = [0 dy./dx];
% plot default annotated peaks
subplot(211);
findpeaks(y,x,'Annotate','extents');
% get peaks with width computed by 'findpeaks'
[pks,locs,peakWidth1,p] = findpeaks(y,x);
subplot(212);
plot(x,y);
hold on
plot(locs,pks,'*m')
% compute starting and ending points
startpoint = zeros(size(pks));
endpoint = zeros(size(pks));
for ii = 1:length(pks)
plot(locs(ii) + peakWidth1(ii)*[-.5 .5],pks(ii) - p(ii)/2 + [0 0],'y')
sp = find((x < locs(ii)) & (dy_dx <= 0),1,'last');
if isempty(sp)
sp = 1;
end
startpoint(ii) = sp;
ep = find((x > locs(ii)) & (dy_dx >= 0),1,'first') - 1;
if isempty(ep)
ep = length(x);
end
endpoint(ii) = ep;
plot(x(startpoint(ii)),y(startpoint(ii)),'og')
plot(x(endpoint(ii)),y(endpoint(ii)),'sr')
end
% compute second type of width using ending and starting points
peakWidth2 = x(endpoint) - x(startpoint);