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Re: Piecewise Functions
Posted:
Aug 7, 1996 3:56 AM


:I am trying to use Mma to solve a model where the system behaves a :certain way up to a point, and an entirely different way after that :point. The result is something like: : :f[x_/;x<4]:=0 :f[x_/;x>=4]:=InterpolatingFunction<<...>> : :This part I can get to work no problem. For part of my analysis, I would :like to take the derivative of the function, but all I get is an identity
oddly, I just ran into the same need. of course,
D[f[x],x]
not knowing which piece of f to apply..can only return:
f'[x]
but D[f[x],x] /. x> 0
gives
f'[0]
where it seems it could just return 0..
i'm stumped..



