Problem with conditional definitions
- To: mathgroup at smc.vnet.net
- Subject: [mg19464] Problem with conditional definitions
- From: "Kevin J. McCann" <kevin.mccann at jhuapl.edu>
- Date: Sat, 28 Aug 1999 15:52:59 -0400
- Organization: Johns Hopkins University Applied Physics Lab, Laurel, MD, USA
- Sender: owner-wri-mathgroup at wolfram.com
I have recently uncovered a problem with conditional definitions of
functions. The following is a simple example
Remove[f]
f[x_ /; x <= 0] := x^2
f[x_ /; 0 < x < 1] := x^3
f[x_ /; x >= 1] := x^4
{f[1.], f'[1.],f''[1.]}
{1.,3.54208,18.8746}
Clearly incorrect. Or
{f[1.1],f'[1.1],f''[1.1]}
{1.4641, 5.28974, 8.77428}
Correct: {1.4641, 5.324, 14.52}
So it is not that the function was evaluated at a boundary.
Also, if I use exact arguments:
{f[1],f'[1],f''[1]}
{1,f'[1],f''[1]}
None of the function definitions lead to the answers I got. Did I miss
something?
--
Kevin J. McCann
Johns Hopkins University APL