[net.crypt] Digram frequencies

pal (05/11/83)

In response to Dave Sibley( ...psuvax!sibley)
Well, it seems that what you have as digram frequencies are actually the 
JOINT probability of the letter pairs, whereas what you would like are
the CONDITIONAL probabilities of the second letter given the first letter.
These are easily obtained from the digram frequencies you have by dividing
them by the probability of occurence of the first letter (these probabilities
should be easily available).