Texas Instruments TI-89, TI-92

Appendix B: Reference Information 565

8992APPBDOC TI

89/TI

92Plus:8992a

bdoc (English) SusanGullord Revised:02/23/01 1:54 PM Printed:02/23/01 2:24 PM Page565 of 34

Regardless of the Complex Format mode setting, undefined variables

are treated as real numbers. To perform complex symbolic analysis,

you can use either of the following methods to set up a complex

variable.

Method 1: Use an underscore _ (TI.89: ¥  TI.92 Plus: 2 ) as

the last character in the variable name to designate a complex

variable. For example:

z_ is treated as a

complex variable

(unless z already

exists, in which case

it retains its existing

data type).

Method 2: Define a complex variable. For example:

x+yi!z

Then z is treated as a

complex variable.

Radian angle mode is recommended for complex number

calculations. Internally, the TI-89 / TI-92 Plus converts all entered trig

values to radians, but it does not convert values for exponential,

logarithmic, or hyperbolic functions.

In Degree angle mode, complex identities such as e^(iq) = cos(q) +

i sin(q) are not generally true because the values for cos and sin are

converted to radians, while those for e^( ) are not. For example,

e^(i45) = cos(45) + i sin(45) is treated internally as e^(i45) =

cos(p/4) + i sin(p/4). Complex identities are always true in Radian

angle mode.

Using Complex

Variables in

Symbolic

Calculations

Note: For best results in

calculations such as

cSolve()

and

cZeros()

, use

Method 1.

Complex Numbers

and Degree Mode

Note: If you use

Degree

angle mode, you must make

polar entries in the form

(rq). In

Degree

angle

mode, an r

entry causes

an error.