Math, Angle, and Test Operations 2-9
NDERIV( (numerical derivative, MATH MATH, item 6) returns
an approximate derivative of an expression with respect to a
specified variable, given the value at which to calculate the
derivative, and H (optional; if none is specified, 1í-3 is used).
NDERIV(expression,variable,value) or
NDERIV(expression,variable,value,H)
NDERIV( uses the symmetric difference quotient method (as
shown in the formula below), which approximates the
numerical derivative value as the slope of the secant line
through the points:
f(X+H)–f(X–H)
f¢(x) =
2H
As H gets smaller, the approximation usually gets more
accurate.
Because of the method used, NDERIV( can return a false
derivative value at a nondifferentiable point.
NDERIV(