[Octave-bug-tracker] [bug #59934] Unexpected complex result from acos

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?59934>

                 Summary: Unexpected complex result from acos
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Sun 24 Jan 2021 01:43:39 AM UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Missed Error or Warning
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 6.1.0
         Discussion Lock: Any
        Operating System: Microsoft Windows

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Details:

Running acos(x) unexpectedly gives complex numbers if x exceeds +1 due to
numerical roundoff, instead of giving a domain error. This unexpected and
undocumented behavior is not listed by "help acos". The workaround now is to
say "acos(max(min(1,x),-1))" to artificially force it to [-1 +1]. Any thoughts
why it returns a complex number?




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