Texas TI-86 用户手册

03MATH.DOC   TI-86, Chap 3, US English   Bob Fedorisko   Revised: 02/13/01 2:19 PM   Printed: 02/13/01 3:00 PM   Page 55 of 10

03MATH.DOC   TI-86, Chap 3, US English   Bob Fedorisko   Revised: 02/13/01 2:19 PM   Printed: 02/13/01 3:00 PM   Page 55 of 10

The built-in variable 

 defines the step size in calculating 

 (in 

 differentiation

mode only) and 

. The built-in variable 

 defines the tolerance in calculating 

, 

,

, and 

. The value of each must be >0. These factors affect the accuracy of the

calculations. As 

 becomes smaller, the approximation typically is more accurate. For

example, 

 returns 

 if 

, but returns 

 if 

 (Appendix).

The function integral error value is stored to the variable 

 (Appendix).

For 

 and 

 while 

 mode is set, these functions are not valid in expression:

, 

, 

, 

, 

, 

, 

, and any equation variable, such as 

.

You can approximate the fourth derivative at the current value of x with this formula:

.

(equal to) Returns 

if valueA is equal to valueB; returns 

 if not equal; valueA and

 can be real or complex numbers, lists, vectors, matrices, or strings

(less than) Returns 

 if valueA is less than valueB; returns 

 if valueA is not less than

; valueA and valueB must be real numbers or lists

(greater than) Returns 

 if valueA is greater than valueB; returns 

 if valueA is not

greater than valueB; valueA and valueB must be real numbers or lists

 

 valueB (less than or equal to) Returns 

 if valueA is less than or equal to valueB; returns 

 if valueA

is not less than or equal to valueB; valueA and valueB must be real numbers or lists

Relational functions are valid
for two lists of the same
length. When  

 and

 are lists, a list of

results calculated element by
element is returned.