${\displaystyle \mathrm {Gradient~of} ~U=grad~U=\nabla {U}={\frac {\partial {U}}{\partial {x}}}\mathbf {i} +{\frac {\partial {U}}{\partial {y}}}\mathbf {j} +{\frac {\partial {U}}{\partial {z}}}\mathbf {k} ;}$
${\displaystyle \nabla }$ is the operator del (q.v.). See Figure C-14 for expressions of the gradient in cylindrical and spherical coordinates. 3. A component of the gradient in an arbitrary direction, as the horizontal gradient of the magnetic field. See also tensor gradient.