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Re: Zeroes and infinities



Nick Maclaren wrote:
Peter Henderson <petercbh@xxxxxxxxxxx> wrote:
Any user who is using a function with a branch cut and who ends up computing 
values near the the branch is going to know about them pretty soon, whether 
they have heard about them or not, in which case they better hope they are in 
the specification.
.
.
.
The problem is with the large number of programs that don't want to
handle them, and where going near a branch cut is an error.
This is a fault at the algorithm level. It is the programmers job to deal with this.
.
.
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If the functions issue a diagnostic on the INITIAL failure, it is
usually easy to find the original mistake.
Well I supose one could ask programming environments to provide special purpose versions that do just this. But would it really help? Such a facility could only be triggerred by hitting the branch point exactly, whereas the error occurs when the branch point is crossed, a far more likely scenario, and this would require the functions to monitor the sequence of calls and determine whether consecutive calls constitute a branch crossing. Really, this is the programmers job.

Regards,
Peter Henderson

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