anonymous function vs local function or M-file function

Dear all, I have a code of curvefitting, it does not display the fitted results. If I replace the anonymous function by a local function (or a M-file function), it works. Would someone explain to me why?

function fitcurv(varargin)
xdata = [8.4 16.6 24.2 31.9 40 48.4];  
ydata = [22.48 34.26 43.88 53.6 60.96 69.38];
fun=@(a,xdata) a(1)* xdata.^a(2);
[a,resnorm] = lsqcurvefit(fun,a0,xdata,ydata);

@[resnorm, a] = lsqcurvefit(@fun,a0,xdata,ydata) ;
% function f= fun(a,xdata)
% f=a(1)* xdata.^a(2);
% end

end

Answer 1

[Star Strider]

It works for me as an anonymous function:

xdata = [8.4 16.6 24.2 31.9 40 48.4];  
ydata = [22.48 34.26 43.88 53.6 60.96 69.38];
a0 = [1 1';]
fun=@(a,xdata) a(1)* xdata.^a(2);
[a,resnorm] = lsqcurvefit(fun,a0,xdata,ydata);

yfit = fun(a,xdata);

figure(1)
plot(xdata, ydata, '+b')
hold on
plot(xdata, yfit, '-r')
hold off
grid

produces:

a =

       5.5706e+000   650.0194e-003

resnorm =

     880.7449e-003

and a good fit when plotted.