Calculator User Manual

Chapter 2: Math, Angle, and Test Operations 60
nDeriv(
nDeriv(nDeriv(
nDeriv(
nDeriv( (numerical derivative) returns an approximate derivative of expression with respect
to
variable, given the value at which to calculate the derivative and H (if not specified, the
default is 1âL3).
nDeriv( is valid only for real numbers.
nDeriv(expression,variable,value[,H])
nDeriv(
uses the symmetric difference quotient method, which approximates the
numerical derivative value as the slope of the secant line through these points.
As H becomes smaller, the approximation usually becomes more accurate.
You can use
nDeriv( once in expression. Because of the method used to calculate nDeriv(,
the TI-84 Plus can return a false derivative value at a nondifferentiable point.
f
′ x()
fx ε+()fx ε–()–
2ε
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