466 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 466 of 132
Loop CATALOG
Loop
block
EndLoop
Repeatedly executes the statements in block.
Note that the loop will be executed endlessly,
unless a Goto or Exit instruction is executed
within block.
block is a sequence of statements separated
with the “:” character.
Program segment:
©
:
1
!i
:Loop
: Ran
d(
6
)
!
d
ie
1
: Ran
d(
6
)
!
d
ie2
: If
d
ie
1
=6 an
d
d
ie2=6
: Goto En
d
: i+
1
!i
:En
d
Loop
:L
bl
En
d
:Disp "T
h
e num
b
er of ro
ll
s is", i
©
LU MATH/Matrix menu
LU matrix, lMatName, uMatName, pMatName[, tol]
Calculates the Doolittle LU (lower-upper)
decomposition of a real or complex matrix.
The lower triangular matrix is stored in
lMatName, the upper triangular matrix in
uMatName, and the permutation matrix
(which describes the row swaps done during
the calculation) in pMatName.
lMatName ù uMatName = pMatName ù matrix
Optionally, any matrix element is treated as
zero if its absolute value is less than tol. This
tolerance is used only if the matrix has
floating-point entries and does not contain
any symbolic variables that have not been
assigned a value. Otherwise, tol is ignored.
• If you use ¥¸ or set the mode to
Exact/Approx=APPROXIMATE, computations
are done using floating-point arithmetic.
• If tol is omitted or not used, the default
tolerance is calculated as:
5Eë14 ùmax(dim(matrix))
ùrowNorm(matrix)
The LU factorization algorithm uses partial
pivoting with row interchanges.
[6,12,18;5,14,31;3,8,18]!m1
¸
6 12 18
5 14 31
3 8 18
LU m1,lower,upper,perm
¸Done
lower ¸
1 0 0
5/6 1 0
1/2 1/2 1
upper ¸
6 12 18
0 4 16
0 0 1
perm ¸
1 0 0
0 1 0
0 0 1
[m,n;o,p]!m1 ¸[]
m n
o p
LU m1,lower,upper,perm
¸Done
lower ¸
1 0
m
o 1
upper ¸
o p
0 n ìmøp
o
perm ¸[]
0 1
1 0