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A Boolean 0/1 function in Mma?

• To: mathgroup at yoda.physics.unc.edu
• Subject: A Boolean 0/1 function in Mma?
• From: mcwilljg at euler.sfasu.edu
• Date: Mon, 2 Nov 92 11:25:52 CST

I am trying to recursively define a piecewise function in the
following manner:

========================
s=0
For[i=0,i<=(n-1), i++,
		s = s + f[y,x[i]]*Indicator[y,x[i],x[i+1]]
   ]
========================

I would like Indicator[y,x[i],x[i+1]] to equal 1 if x[i]<= y <=x[i+1]
and 0 otherwise.

For example, on many programmable cauculators this is how it would be
accomplished:

	f(y) = (Exp(y))*(0 <= y <= 1) + (Sin(y))*(1 <= y <= 2)
	
	where (x[i] <= y <= x[i+1]) is 1 if true and 0 otherwise.

Does Mma have such a function defined?

If not, how could I do the same thing?  Mma gives "True" or "False"  
to 

(x[i] <= y <= x[i+1]), can this be converted to 1 or 0?

Thanks in advance for any help.

---
Joseph McWilliams
mcwilljg at euler.sfasu.edu