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Topic: extract from Reduce
Replies: 2   Last Post: Apr 4, 2013 10:30 PM

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Albert Retey

Posts: 688
Registered: 7/15/08
Re: extract from Reduce
Posted: Apr 4, 2013 10:29 PM
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Hi,

> I have a result from the command Reduce that looks like this (as an
> example):
>
> a:= x==3||x==4||x==7
>
> I need to extract the numbers but I can't find a nice way to handle
> the case when there is only one equation, for instance:
>
> a:= x==6
>
> currently I check what the head of the expression is (Head[a]) and
> handle the case Head[a]=Or with a Map[] and the case Head[a]="Equal"
> with a[[2]]. Not very nice, but I guess that there is a neat way to
> do it.
>


There might be more efficient ways to do this, but I think this is clear
and compact:

Cases[{a}, Equal[x, v_?NumericQ] :> v, Infinity]

hth,

albert




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