Texas Instruments TI-89 User Manual - Page 838

LnReg MATH/Statistics/Regressions menu LnReg list1, list2[, [list3] [, list4, list5]] In function graphing mode: 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. {1,2,3,4,5,6,7,8}! L1 ¸ {1,2,2,3,3,3,4,4}! L2 ¸ LnReg L1,L2 ¸ ShowStat ¸ {1 2 3 ...} {1 2 2 ...} Done 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. 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 838 Appendix A: Functions and Instructions