Texas Instruments TI-86 - Page 292

280
Chapter 20: A to Z Function and Instruction Reference
20ATOZ.DOC TI-86, Chap 20, US English Bob Fedorisko Revised: 02/13/01 2:42 PM Printed: 02/13/01 3:05 PM Page 280 of 118
DelVar(
‡ program editor
CTL menu
(DelVa shows
on menu)
DelVar(
variable
)
Deletes the specified user-created
variable
from
memory.
You cannot use
DelVar(
to delete a program variable or
built-in variable.
2
¶
A
b
2
(A+2)
2
b
16
DelVar(A)
b
Done
(A+2)
2
b
ERROR 14 UNDEFINED
der1(
CALC menu
der1(
expression
,
variable
,
value
)
Returns the first derivative of
expression
with respect
to
variable
at the real or complex
value
.
der1(x^3,x,5)
b
75
der1(
expression
,
variable
)
Uses the current value of
variable
.
3
¶
x
b
3
der1(x^3,x)
b
27
der1(
expression
,
variable
,
list
)
Returns a list containing the first derivatives at the
values specified by the elements in
list
.
der1(x^3,x,{5,3})
b
{75 27}
der2(
CALC menu
der2(
expression
,
variable
,
value
)
Returns the second derivative of
expression
with
respect to
variable
at the real or complex
value
.
der2(x^3,x,5)
b
30
der2(
expression
,
variable
)
Uses the current value of
variable
.
3
¶
x
b
3
der2(x^3,x)
b
18
der2(
expression
,
variable
,
list
)
Returns a list containing the second derivatives at the
values specified by the elements in
list
.
der2(x^3,x,{5,3})
b
{30 18}