Texas Instruments TI-89 Tip List page 96

©Rank 3 matrix
©25oct00 dburkett@infinet.com
local a1,a2
intdiv(i-1,d[2]*d[3])+1→a1
intdiv(i-1-(a1-1)*d[2]*d[3],d[3])+1→a2
{a1,a2,i-d[3]*(d[2]*(a1-1)+a2-1)}
EndFunc
Find element address for a rank-4 array:
m4aind(i,d)
Func
©(index,{d1,d2,d3,d4}) return {a1,a2,a3,a4}
©Rank 4 matrix
©25oct00 dburkett@infinet.com
local a1,a2,a3
intdiv(i-1,d[2]*d[3]*d[4])+1→a1
intdiv(i-1-(a1-1)*d[2]*d[3]*d[4],d[3]*d[4])+1→a2
intdiv(i-1-((a1-1)*d[2]*d[3]*d[4]+(a2-1)*d[3]*d[4]),d[4])+1→a3
{a1,a2,a3,i-d[4]*(d[3]*(d[2]*(a1-1)+a2-1)+a3-1)}
EndFunc
Find element address for array of any rank:
mnaind(i,d)
Func
©mnaind(i,dims) returns the array location of ith list element
©Bhuvanesh Bhatt, Nov 2000
Local j,k,l,jj,a,dd
dim(d)→dd
1→d[dd+1]
1+dd→dd
true→jj
For l,1,dd
d[l]→k
If getType(k)≠"NUM" then
false→jj
Exit
EndIf
EndFor
If getType(i)="NUM" and jj and i>product(d):Return {}
For l,1,dd-1
when(l≠1,intDiv(i-1-Σ((a[j]-1)*‹(d[jj],jj,j+1,dd),j,1,l-1),‹(d[k],k,l+1,dd)),int
Div(i-1,‹(d[jj],jj,2,dd)))+1→a[l]
EndFor
a
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