M-file, single-variable function integration and boundary on fixed interval

%This is a simple f(x) function
function y =bumpy(x)
%this function draws a bumpy curve

y=1/(4*pi)*(1./((x-2).^2+1)+1./((x+0.5).^4+32)+1./((x+1).^2+2));
%This is how to integrate the function on (-3,3), with tolerance of 10^(-6)
quad('bumpy', -3, 3, 10^(-6))
%This is how to find the minimum boundary of x and y, on (-1.2, 1)
xmin=fminbnd('bumpy',-1.2, 1)
ymin=bumpy(xmin)
%How to find the maximun boundary?
%find minimum boundary for y=-f(x)



%This is example is from Introduction to Matlab with numerical preliminaries by Alexander Stanoyevitch.