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MathGroup Archive 1993

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RE: recursive function

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: RE: recursive function
  • From: Joseph G. Mcwilliams <mcwilljg at euler.sfasu.edu>
  • Date: Mon, 27 Sep 93 11:43:29 -0500

Thanks to all who responded to my query on the recursive problem, especially  Malcolm Crawford and Roberto Sierra.

There were two errors in the original posting.  A typo, a>=  n*(n-1)/2 should have read a>=  n*(n+1)/2, and an outright  
error; the above  should read a > n*(n+1)/2.  The equality causes infinite recursion.

For those interested, a Mathematica code that works is:

f[n_Integer,0] := 1;
f[n_Integer,a_Integer] := 0 /; a<0;
f[n_Integer,a_Integer] :=
	f[n,a] = If[ a>n (n+1)/2,
		f[n,n (n+1)/2],
		f[n-1,a] + f[n-1,a-n]
	];

================================================================
Joseph McWilliams
Math/SFASU/Nacogdoches/TX
mcwilljg at euler.sfasu.edu
================================================================





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