Texas Instruments TITANIUM TI-89 - Manual (Page 838)

838 Appendix A: Functions and Instructions
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