Texas Instruments TI-89 Tip List page 93

{e e e e
1,1,1 1,1,2 1,2,1 1,2,2
For a particular element location {a
k = a 3 + a 2 − 1 d 3 + a 1 − 1 d 2 d 3
This can be expanded and factored to eliminate one multiply, and access each variable only once, like
this:
k = d 3 d 2 a 1 − 1 + a 2 − 1 + a 3
The routines to save and recall elements to a 3-dimensional array are called m3sto() and m3rcl().
m3sto() looks like this:
m3sto(v,l,d,m)
Func
©(value,location{},dim{},matrix{})
©Store value in 3D matrix
©12oct00 dburkett@infinet.com
v→m[d[3]*(d[2]*(l[1]-1)+l[2]-1)+l[3]]
m
EndFunc
where
v is the value to store in the array
l is a 3-element list that specifies the element location as {a
d is a 3-element list that specifies the list dimensions as {d
m is the array list or the name of the array list
m3sto() returns the original array m with value v stored at location l.
For example, if we want to put 7 at location {1,2,3} in array mat1, which has dimensions 2 x 3 x 4, then
use this:
m3sto(7,{1,2,3},{2,3,4},mat1)→mat1
To recall an array element, use m3rcl():
m3rcl(l,d,m)
Func
©(location{},dim{},matrix{})
©Recall element from 3D matrix
©12oct00 dburkett@infinet.com
m[d[3]*(d[2]*(l[1]-1)+l[2]-1)+l[3]]
EndFunc
where
l is a 3-element list that specifies the element location as {a
e e e e }
2,1,1 2,1,2 2,2,1 2,2,2
, a , a }, we can find the corresponding list element index k from
1 2 3
, a , a }
1 2 3
, d , d }
1 2 3
, a , a }
1 2 3
[1]
[2]
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