A normal derivative is a directional derivative taken in the direction normal (that is, orthogonal) to some surface in space, or more generally along a normal vector field orthogonal to some hypersurface. See for example Neumann boundary condition. If the normal direction is denoted by, then the directional derivative of a function ƒ is sometimes denoted as . In other notations
Read more about this topic: Directional Derivative
Famous quotes containing the words normal and/or derivative:
“To try to control a nine-month-old’s clinginess by forcing him away is a mistake, because it counteracts a normal part of the child’s development. To think that the child is clinging to you because he is spoiled is nonsense. Clinginess is not a discipline issue, at least not in the sense of correcting a wrongdoing.”
—Lawrence Balter (20th century)
“Poor John Field!—I trust he does not read this, unless he will improve by it,—thinking to live by some derivative old-country mode in this primitive new country.... With his horizon all his own, yet he a poor man, born to be poor, with his inherited Irish poverty or poor life, his Adam’s grandmother and boggy ways, not to rise in this world, he nor his posterity, till their wading webbed bog-trotting feet get talaria to their heels.”
—Henry David Thoreau (1817–1862)