function faz_histograma( x, Nc=20 )
N = length( x );
xm = mean( x );
sx = std( x );
fGaus = @(x,x0,sx)( 1/(sqrt(2*pi)*sx)* ...
                    exp( -0.5*( (x-x0)/sx ).^2 ) );
xis = (xm-5*sx) : 0.1*sx : (xm+5*sx);
[nc,xc] = hist( x, Nc );
dxc = xc(2)-xc(1);

hist( x, Nc );
hold on
plot( xis, N*dxc*fGaus( xis, xm, sx), '-r' )