detecting lisp overflow



On Mar. 18, 2013, Stavros Macrakis wrote:
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>Try the following test instead:
>
>:lisp (float-inf-p (elt (list 100.0 (exp 1000.0)) 1))
>
>In some Lisp implementations, exp(1000) will give an error, but if it
>doesn't, and gives an INF, this should work.
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This works, but if I follow your drift, you seem to be
suggesting that I rewrite adaptive-plot to return a more
informative output list, using, say, some mutation of

(if (float-inf-p (fun x))
    (cons x (cons 'INF mylist))
    (cons x (cons (fun x) mylist)))

In gcl, I get the behavior:

(%i2) :lisp (float-inf-p (elt (list 100.0 (exp 1000.0)) 1))
T

(%i2) :lisp (float-inf-p (exp 1000.0))
T

Ted