Problem with Gaussian fit to Data

What is wrong with this Gaussian Fit:

gaussEqn = 'a*exp(-((x-b)/c)^2)+d'
f = fit(xdata.',ydata.',gaussEqn)
%Results of fit
coeffs=coeffvalues(f);
a=coeffs(1)
b=coeffs(2)
c=coeffs(3)
d=coeffs(4)
    xValue=7;
    sp=3;
%Create fine data to plot fit
xdataF=(linspace(xValue-sp,xValue+sp,10*sp))
fitGaus =  a*exp(-((xdataF-b)/c)^2)+d

yvalue=ym;
xpeak=xdataF(find(fity==ym));
xpeak=mean(xpeak(:));   %Take mean incase more than one peak found

the fit is fine:

f = 

       General model:
       f(x) = a*exp(-((x-b)/c)^2)+d
       Coefficients (with 95% confidence bounds):
         a =      0.7094
         b =      0.7547
         c =       0.276
         d =        1482  (-1823, 4787)

But I get the error:

Error using  ^ 
Inputs must be a scalar and a square matrix.
To compute elementwise POWER, use POWER (.^) instead.

Error in HiSeqDistortionTool>fitLocalPeak (line 726)
fitGaus =  a*exp(-((xdataF-b)/c)^2)+d

Answer 1

[Thorsten]

 gaussEqn = 'a*exp(-((x-b)/c).^2)+d'

[Jason]

OK thanks. I'm still running into problems. This is my x&y data:

ydata =

           0         814        2254        4636        3608        1355          65

xdata =

     4     5     6     7     8     9    10

I want to do the fit, and then plot at a higher resolution and then find the max y and x value of this in high resolution fit.

%Gaussian Fit--------------------------------------------------------
gaussEqn = 'a*exp(-((x-b)/c).^2)+d'
f = fit(xdata',ydata',gaussEqn)

%Results of fit
coeffs=coeffvalues(f);
a=coeffs(1)
b=coeffs(2)
c=coeffs(3)
d=coeffs(4)
figure

plot(xdata',ydata','r.')  %plot raw data
hold on;
plot(f,'r--')             %plot fit

%Increase resolution of x data
xdataFine=(linspace(xdata(1),xdata(end),30))  
%plot high res fit
fitGaus =  a*exp(-((xdataFine-b)/c).^2)+d
plot(fitGaus,'g-')
hold off.

%Find max value and its x location
ym=max(fitGaus);
yvalue=ym;
xpeak=xdataFine(find(fitGaus==ym));
xpeak=mean(xpeak(:));   %Take mean incase more than one peak found