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12/20/12 6:44pm

You are making assumptions about k that need to be explicit.

In[1]:= f[t_, k_, a_] := a*t^k

In[2]:= f[0, k, a]

Out[2]= 0 a

In[3]:= Simplify[%, k > 0]

Out[3]= 0

What would happen if k were negative?

In[4]:= 0^(-3)
Power::infy: Infinite expression 0 encountered.

Out[4]= ComplexInfinity

If you really, really want f[0,..,..] to be zero regardless of the other arguments, you can make a second, more specific, definition.

In[8]:= f[0, k_, a_] := 0

In[9]:= f[0, -2, 137]

Out[9]= 0

Since this definition of f is more specific than the earlier definition, it will be tried first.

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Subject (listing for 'Function evaluated at 0')
Author Date Posted
Function evaluated at 0 Morten Valberg 12/20/12 10:08am
Re: Function evaluated at 0 jf 12/20/12 6:44pm
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