partial derivative
tends to a limit as h → 0, this limit is the partial derivative of f, at the point (x1, x2,…, xn), with respect to x1; it is denoted by f1(x1, x2,…, xn) or ∂f/∂x1 (read as ‘partial d f by d x1'). This partial derivative may be found using the normal rules of differentiation, by differentiating as though the function were a function of x1 only and treating x2,…, xn as constants. The other partial derivatives,
are defined similarly. The partial derivatives may also be denoted by 
For example, if f(x,y) = xy3, then the partial derivatives are fx = y3 and fy = 3xy2. See also chain rule (multivariable), differential (multivariate case), directional derivative, higher-order partial derivative, Jacobian matrix.
- substitution group
- subtend
- subtraction
- sufficient condition
- sufficient estimator
- sufficiently large
- sufficient statistic
- sum
- summation notation
- sum to infinity
- sup
- superadditive
- superposition principle
- superscript
- supersink
- supersource
- supplementary angles
- supplementary unit
- support
- supremum
- surd
- surface
- surface
- surface
- surface area