difference equation

<mathematics>

A relation between consecutive elements of a sequence. The first difference is 

 D u(n) = u(n+1) - u(n)
where u(n) is the nth element of sequence u. The second difference is 

 D2 u(n) = D (D u(n))
 	= (u(n+2) - u(n+1)) - (u(n+1) - u(n))
 	= u(n+2) - 2u(n+1) + u(n)
And so on. A recurrence relation such as 

 u(n+2) + a u(n+1) + b u(n) = 0
can be converted to a difference equation (in this case, a second order linear difference equation): 

 D2 u(n) + p D u(n) + q u(n) = 0
and vice versa. a, b, p, q are constants.

Last updated: 1995-02-10

Nearby terms:

Difference Engine ♦ difference equation ♦ differential backup ♦ differential driver

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