Texas Instruments TI-89 사용자 설명서

Symbolic Manipulation

 240

Using Exact, Approximate, and Auto Modes

Using Exact, Approximate, and Auto Modes

Using Exact, Approximate, and Auto Modes

Using Exact, Approximate, and Auto Modes

The Exact/Approx mode settings, which are described briefly in Operating the Handheld, 
directly affect the precision and accuracy with which the TI-89 Titanium calculates a 
result. This section describes these mode settings as they relate to symbolic 
manipulation.

EXACT Setting

EXACT Setting

EXACT Setting

EXACT Setting

When Exact/Approx = EXACT, the handheld uses exact rational arithmetic with up to 
614 digits in the numerator and 614 digits in the denominator. The EXACT setting:

•

Transforms irrational numbers to standard forms as much as possible without 
approximating them. For example, 

 transforms to 

 and 

 transforms 

to 

.

•

Converts floating-point numbers to rational numbers. For example, 0.25 transforms 
to 1/4

.

The functions 

, 

, 

, 

, 

, ‰, 

, and 

 use only exact 

symbolic algorithms. These functions do not compute approximate solutions in the 
EXACT setting.

•

Some equations, such as 

Lx

, have solutions that cannot all be finitely 

represented in terms of the functions and operators on the handheld. 

12

2 3