I don't understand why you changed the limit to a limit as x approaches 0 from a limit as x approaches 1/a? If you are
going to return a noun form you could just return
'limit(signum(a*x+b),x,1/a)
?
Rich
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From: "Barton Willis" <willisb at unk.edu>
Sent: Wednesday, February 03, 2010 8:24 PM
To: "Richard Hennessy" <rich.hennessy at verizon.net>
Cc: <maxima at math.utexas.edu>
Subject: Re: [Maxima] limits of signum expressions
> limit(signum(a*x+b),x,1/a) = 'limit(signum(a*x+b+1),x,0) is OK, but
> limit(signum(a*x+b),x,1/a) = signum(b+1) is wrong. To see this
> let a = 1 and b = -1, then then limit(signum(x-1),x,1) = und # signum(-1
> +1).
>
> Barton
>
> -----maxima-bounces at math.utexas.edu wrote: -----
>
>
>>(%i13) limit(signum(a*x+b),x,1/a);
>>(out13) 'limit(signum(a*x+b+1),x,0)
>>
>>The plus one is okay but a*x should not be in there. I think the answer
>>should be 'limit(signum(b+1),x,0) or just
>>signum(b+1).
>
>