Why doesn't hold work with histogram and plot? How do I plot fit distribution on top of histogram?

The following code fails to plot the probability function on top of the histogram, producing only the figure below. It appears hold does not work with histogram. How do I use plot and histogram together in the same figure?

x = [-2:.1:2];
figure
 subplot(1,3,1)
  histogram(InterfractionalMotion.x)
  hold
  plot(x,normpdf(x,normal.x.mu,normal.x.sigma))
  hold off
  xlabel('Left, mm')
 subplot(1,3,2)
  hold
  histogram(InterfractionalMotion.y)
  plot(x,normpdf(x,normal.y.mu,normal.y.sigma))
  hold off
  xlabel('Posterior, mm')
 subplot(1,3,3)
  hold
  histogram(InterfractionalMotion.z)
  plot(x,normpdf(x,normal.z.mu,normal.z.sigma))
  hold off
  xlabel('Superior, mm')

When I execute the script, the MATLAB console outputs:

Current plot held
Current plot held
Current plot held

[Daniel Bridges]

I have found that it is working to plot both in the same subplot, but that the histogram must be normalized to 1 for it to be displayed as desired.

Answer 1

[Daniel Bridges]

The following code results in scaling the probability distribution.

x = [-20:.1:20];
f = figure;
p = uipanel('Parent',f,'BorderType','none'); 
p.Title = 'Interfractional Motion Per DICOM Axis'; 
p.TitlePosition = 'centertop'; 
p.FontSize = 12;
p.FontWeight = 'bold';
 subplot(1,3,1,'Parent',p)
  histx = histogram(InterfractionalMotion.x);
  hold
  plot(x,max(histx.Values)*normpdf(x,normal.x.mu,normal.x.sigma),'k')
  hold off
  xlabel('Left, mm')
 subplot(1,3,2,'Parent',p)
  hold
  histy = histogram(InterfractionalMotion.y);
  plot(x,max(histy.Values)*normpdf(x,normal.y.mu,normal.y.sigma),'k')
  hold off
  xlabel('Posterior, mm')
 subplot(1,3,3,'Parent',p)
  histz = histogram(InterfractionalMotion.z);
  hold
  plot(x,max(histz.Values)*normpdf(x,normal.z.mu,normal.z.sigma),'k')
  hold off
  xlabel('Superior, mm')

... but are these really the best fit normal distributions to this data?