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Re: Handling of invalid arguments

This page is part of the web mail archives of SRFI 77 from before July 7th, 2015. The new archives for SRFI 77 contain all messages, not just those from before July 7th, 2015.

On Jun 29, 2006, at 9:15 AM, Marc Feeley wrote:

I have noticed that the specification of flexpt, flsqrt, flatan and many other procedures may return a meaningless result for certain ranges of arguments.

I think "that's not a bug, that's a feature," to coin a phrase. I believe the intention is to let

(flsqrt -1.0)

return whatever the hardware sqrt function returns (a NaN in IEEE 754 arithmetic) rather than

> (sqrt -1.0)

which is what Gambit returns. I believe the intent is to somehow map the <math.h> C functions to Scheme functions; any author of the SRFI want to comment here?

In other words, this defines a new set of underspecified procedures that return what expt, sqrt, atan, ... would return if the arguments are within a certain range (I'm not sure this is spelled out explicitly), but which can return almost anything else for other arguments.