Reputation: 2369
Answered on Math.SE, generating matrix for a recurrence relation
for the recurrence f(n)=a*f(n-1)+b*f(n-2)+c*f(n-3)+d*f(n-4)
, how can one get the generating matrix so that it can be solved by matrix exponentiation?
For f(n)=a*f(n-1)+b*f(n-2)+c*f(n-3)
the corresponding generating matrix is:
| a 0 c | | f(n) | | f(n+1) |
| 1 0 0 | x | f(n-1) | = | f(n) |
| 0 1 0 | | f(n-2) | | f(n-1) |
so how to get the same for required recurrence? Also what should be the procedure for any recurrence which may be of the form :
f(n)=a*f(n-1)+b*f(n-2)+c*f(n-3)+..+someconstant*f(n-k)
?
Thanks.
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