Calculator User Manual

TI-83 Plus Math, Angle, and Test Operations 70
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 1
â
L
3).
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.
ε
εε
2
)(()(
)('
−−+
=
xfxf
xf
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-83 Plus can return a false derivative value at a
nondifferentiable point.