For a function of two variables z=f(x,y), the gradient is the two-dimensional vector <f_x(x,y),f_y(x,y)>. This definition generalizes in a natural way to functions of more than three variables. For the function z=f(x,y)=4x^2+y^2.
By this definition, about 10% of people who smoke marijuana become addicted to it. (More on Time.com: PHOTOS â Cannabis Conventions). However, nonspecialists (including many doctors) still tend to use an older perspective, now seen as outdated by experts.
Though you may have heard otherwise, marijuana can be addictive: Nearly 10% of people who use it become dependent on it. It isnât clear whether marijuana is a gateway drug that makes people more likely to try harder drugs like cocaine and heroin. The amount of THC in marijuana has gone up in recent years.