Why is fsurf complaining when it plots -e^(-x^2)?

I wanted to plot:

with fsurf however, when I tried it complained about errors, what I did was:

    >> fsurf(@(x,y) -exp( -(x)^2), [-10 10 -10 10])

why does that give the following error:

Warning: Function behaves unexpectedly on array inputs. To
improve performance, properly vectorize your function to return
an output with the same size and shape as the input arguments. 
> In matlab.graphics.function.FunctionSurface>getFunction
  In matlab.graphics.function.FunctionSurface/updateFunction
  In matlab.graphics.function.FunctionSurface/set.Function
  In matlab.graphics.function.FunctionSurface
  In fsurf>singleFsurf (line 261)
  In fsurf>@(f)singleFsurf(cax,{f},extraOpts,args) (line 227)
  In fsurf>vectorizeFsurf (line 227)
  In fsurf (line 200) 
>>

????

the plot it gives is ugly:

Answer 1

[Star Strider]

The warnings disappear if you use element-wise operations (the ‘dot operator’ for the exponentiation), and the plot looks better if you reduce the x-range:

fsurf(@(x,y) -exp( -(x).^2), [-5 5 -10 10])