Texas Instruments PLUS TI-89 - Manual (Page 553)

536 Appendix A: Functions and Instructions
8992APPA.DOC TI-89 / TI-92 Plus: Appendix A (US English) Susan Gullord Revised: 02/23/01 1:48 PM Printed: 02/23/01 2:21 PM Page 536 of 132
¡ , ', " 2 “ key ( ¡ ), 2 È key ('), 2 É key (")
dd ¡mm ' ss.ss " ⇒ expression
dd A positive or negative number
mm A non-negative number
ss.ss A non-negative number
Returns dd +( mm /60)+( ss.ss /3600).
This base-60 entry format lets you:
•
Enter an angle in degrees/minutes/seconds
without regard to the current angle mode.
•
Enter time as hours/minutes/seconds.
In Degree angle mode:
25°13'17.5" ¸ 25.221...
25°30' ¸ 51/2
' (prime) 2 È key
variable '
variable ''
Enters a prime symbol in a differential
equation. A single prime symbol denotes a
1st-order differential equation, two prime
symbols denote a 2nd-order, etc.
deSolve(y''=y^(ë 1/2) and
y(0)=0 and y'(0)=0,t,y) ¸
2øy 3/4
3
=t
_ (underscore) TI - 89: ¥  key TI - 92 Plus: 2  key
expression _ unit
Designates the units for an expression . All
unit names must begin with an underscore.
You can use pre-defined units or create
your own units. For a list of pre-defined
units, refer to the chapter about constants
and measurement units in this book. You
can press:
TI-89: 2 9
TI-92 Plus: ¥ À
to select units from a menu, or you can
type the unit names directly.
3_m 4 _ft ¸ 9.842…ø_ft
Note: To type 4, press 2 Ž .
variable _
When variable has no value, it is treated as
though it represents a complex number. By
default, without the _
, the variable is
treated as real.
If variable has a value, the _ is ignored and
variable retains its original data type.
Note: You can store a complex number to
a variable without using _ . However, for
best results in calculations such as cSolve()
and cZeros() , the _ is recommended.
Assuming z is undefined:
real(z) ¸ z
real(z_) ¸ real(z_)
imag(z) ¸ 0
imag(z_) ¸ imag(z_)