'Copyright 2000 The American Cryptogram Association (ACA)    
'3613 Piedmont Drive, Plano TX 75075-6234    
'All rights reserved.    
    
'DiAvg.Bas contains the function  
'DiAvg() and DiSum() introduced  
'in May/Jun 2001 and corrected  
'in the Nov/Dec 2001 Computer Column.  
'See those two Columns as well as  
'Sep/Oct 2001 for details about how  
'to use these functions in programs.  
    
'Corrected Nov/Dec 2001    
Function DiAvg(S$,A)    
 DLen%= Len(S$) - 1    
 If A<>1 then Dlen%=((Dlen%-1)\2)+1    
 DiAvg = Int(100*(DiSum(S$,A)/Dlen%))    
End Function 'DiAvg    
    
Function DiSum(S$,A) Static    
IF Init%=0 Then    
DIM Di%(26,26)    
d$=d$+"47874675736879373989676574742"    
d$=d$+"08111630721710653712060825273"    
d$=d$+"28727621822647613040765686558"    
d$=d$+"43665753677656062978887667458"    
d$=d$+"79775998577673745376447226538"    
d$=d$+"40757624050755475577326557527"    
d$=d$+"66635051854494348315548426576"    
d$=d$+"25050758777744258797647884735"    
d$=d$+"05500040003000005000006000005"    
d$=d$+"43274246224365313653040508557"    
d$=d$+"85448258548524666550718643842"    
d$=d$+"47104647613656140608678869684"    
d$=d$+"66568535896563626677686663678"    
d$=d$+"97729789684537333732672173276"    
d$=d$+"07666030400000000000000000000"    
d$=d$+"06000008667966583666686368865"    
d$=d$+"60718676865784666687458974706"    
d$=d$+"28665865983366596278874707266"    
d$=d$+"76646462377856088833434361008"    
d$=d$+"00070000050001021003073347328"    
d$=d$+"72244673055521403141424203510"    
d$=d$+"11035012520223066666655633565"    
d$=d$+"86357643624240005000300200300"    
d$=d$+"010200044"    
For I%=0 to 675 'Build Di% Table    
  C$=Mid$(D$,I%+1,1): V% = Val(C$)    
  Di%((I%\26)+1,(I% mod 26)+1)=V%    
Next I%    
d$="" : Init%=1 'Initialization done    
End If    
TLen%=Len(S$)-1 : Sum%=0 :Stp%=2    
If A=1 Then Stp%=1    
For I%=1 to TLen% Step Stp%    
  R%=Asc(Mid$(S$,I%,1))-64    
  C%=Asc(Mid$(S$,I%+1,1))-64    
  Sum%=Sum%+Di%(R%,C%)    
Next I%    
DiSum = Sum%    
End Function 'DiSum