Texas Instruments PLUS TI-89 - Manual (Page 481)

464 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 464 of 132
LnReg MATH/Statistics/Regressions menu
LnReg list1 , list2 [ , [ list3 ] [, list4 , list5 ] ]
Calculates the logarithmic regression and
updates all the system statistics variables.
All the lists must have equal dimensions
except for
list5 .
list1 represents xlist.
list2 represents ylist.
list3 represents frequency.
list4 represents category codes.
list5 represents category include list.
Note: list1 through list4 must be a variable
name or c1–c99 (columns in the last data
variable shown in the Data/Matrix Editor).
list5 does not have to be a variable name and
cannot be c1–c99.
In function graphing mode:
{1,2,3,4,5,6,7,8}! L1 ¸
{1 2 3 ...}
{1,2,2,3,3,3,4,4}! L2 ¸
{1 2 2 ...}
LnReg L1,L2 ¸ Done
ShowStat ¸
¸
Regeq(x) "y1(x) ¸ Done
NewPlot 1,1,L1,L2 ¸ Done
¥ %
Local CATALOG
Local var1 [, var2 ] [, var3 ] ...
Declares the specified vars as local variables.
Those variables exist only during evaluation
of a program or function and are deleted
when the program or function finishes
execution.
Note: Local variables save memory because
they only exist temporarily. Also, they do not
disturb any existing global variable values.
Local variables must be used for
For loops
and for temporarily saving values in a multi-
line function since modifications on global
variables are not allowed in a function.
Program listing:
:prgmname()
:Prgm
:Local x,y
:Input "Enter x",x
:Input "Enter y",y
:Disp xù y
:EndPrgm
Note: x and y do not exist after the
program executes.
Lock CATALOG
Lock var1 [, var2] ...
Locks the specified variables. This prevents
you from accidentally deleting or changing
the variable without first using the unlock
instruction on that variable.
In the example to the right, the variable L1 is
locked and cannot be deleted or modified.
Note: The variables can be unlocked using
the Unlock command.
{1,2,3,4}! L1 ¸ {1,2,3,4}
Lock L1 ¸ Done
DelVar L1 ¸
Error: Variable is locked or protected