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# Maple problems watch

1. i don't know what on earth i'm doing wrong here.

i have

restart;
assume(hbar,positive);
assume(omega,positive);
assume(alpha,positive);
assume(m,positive);
f1:= (x,alpha)-> piecewise(abs(alpha*x)<=Pi/2,cos(alpha*x),0):
f1(x,alpha);
Df1:=diff(f1(x,alpha),x,x);

now Df1 displays that
don't know why that code above isn't working but basically Df1 says f1'' is undefined at pi/(2*alpha).

as far as i'm aware the at since and this is screwing up the rest of my worksheet. what am i doing wrong?

i attach the LaTeX code for the bit i can't get working in case you want to try and get it working to see it properly:
\cases{0& x<-1/2\,{\frac {\pi }{{\it alpha}}} \cr {\it undefined}& x=-1/2\,{\frac {\pi }{{\it alpha~}}} \cr -\cos \left( {\it alpha~}\,x \right) {{\it alpha~}}^{2}& x<1/2\,{\frac {\pi }{{\it alpha}}} \cr {\it undefined}& x=1/2\,{\frac {\pi }{{\it alpha}}} \cr 0& 1/2\,{\frac {\pi }{{\it alpha~}}}<x \cr}
2. never mind. realised where the problem was.

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Updated: January 27, 2010
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