Displaying 20 results from an estimated 1000 matches similar to: "BUG: atan(1i) / 5 = NaN+Infi ?"
2024 Sep 06
1
BUG: atan(1i) / 5 = NaN+Infi ?
G.5.1 para 2 can be found in the C17 standard -- I actually have the
final draft not the published standard. It's in earlier standards, I
just didn't check earlier standards. Complex arithmetic was not in
the first C standard (C89) but was in C99.
The complex numbers do indeed form a field, and Z*W invokes an
operation in that field when Z and W are both complex numbers. Z*R
and R*Z,
2024 Sep 05
0
BUG: atan(1i) / 5 = NaN+Infi ?
On 2024-09-05 6:12 p.m., Leo Mada wrote:
> Dear Duncan,
>
> Here is also the missing information:
> R version 4.4.1 (2024-06-14 ucrt)
> Platform: x86_64-w64-mingw32/x64
> Running under: Windows 10 x64 (build 19045)
>
> Regarding the results:
> atan(1i)
> #?0+Infi
> Re(atan(1i))
> # 0
> Im(atan(1i))
> #? Inf
>
> 0 + Inf i is a valid complex number:
2024 Sep 05
1
BUG: atan(1i) / 5 = NaN+Infi ?
Dear Bert,
These behave like real divisions/multiplications:
complex(re=Inf, im = Inf) * 5
# Inf+Infi
complex(re=-Inf, im = Inf) * 5
# -Inf+Infi
The real division / multiplication should be faster and also is well behaved. I was expecting R to do the real division/multiplication on a complex number. Which R actually does for these very particular cases; but not when only Im(x) is Inf.
2024 Sep 05
2
BUG: atan(1i) / 5 = NaN+Infi ?
Dear R Users,
Is this desired behaviour?
I presume it's a bug.
atan(1i)
# 0+Infi
tan(atan(1i))
# 0+1i
atan(1i) / 5
# NaN+Infi
There were some changes in handling of complex numbers. But it looks like a bug.
Sincerely,
Leonard
[[alternative HTML version deleted]]
2024 Sep 06
1
BUG: atan(1i) / 5 = NaN+Infi ?
I expect that atan(1i) = (0 + infinity i) and that atan(1i)/5 = (0 +
infinity i)/5 = (0 + infinity i).
Here's what I get in C:
(0,1) = (0, 1)
atan((0,1)) = (0, inf)
atan((0,1))/5 = (0, inf)
Note the difference between I*infinity = (0,1)*infinity =
(0*infinity,1*infinity) = (NaN,infinity)
and (0,infinity)/5 = (0/5,infinity/5) = (0,infinity).
The former involves multiplying 0 by infinity, which
2024 Sep 05
1
BUG: atan(1i) / 5 = NaN+Infi ?
> complex(real = 0, imaginary = Inf)
[1] 0+Infi
> Inf*1i
[1] NaN+Infi
>> complex(real = 0, imaginary = Inf)/5
[1] NaN+Infi
See the Note in ?complex for the explanation, I think. Duncan can correct
if I'm wrong.
-- Bert
On Thu, Sep 5, 2024 at 3:20?PM Leo Mada <leo.mada at syonic.eu> wrote:
> Dear Bert,
>
> These behave like real divisions/multiplications:
>
2024 Sep 05
3
BUG: atan(1i) / 5 = NaN+Infi ?
On 2024-09-05 4:23 p.m., Leo Mada via R-help wrote:
> Dear R Users,
>
> Is this desired behaviour?
> I presume it's a bug.
>
> atan(1i)
> # 0+Infi
>
> tan(atan(1i))
> # 0+1i
>
> atan(1i) / 5
> # NaN+Infi
There's no need to involve atan() and tan() in this:
> (0+Inf*1i)/5
[1] NaN+Infi
Why do you think this is a bug?
Duncan Murdoch
2024 Sep 05
2
BUG: atan(1i) / 5 = NaN+Infi ?
Perhaps
> Inf*1i
[1] NaN+Infi
clarifies why it is *not* a bug.
(Boy, did that jog some long dusty math memories :-) )
-- Bert
On Thu, Sep 5, 2024 at 2:48?PM Duncan Murdoch <murdoch.duncan at gmail.com>
wrote:
> On 2024-09-05 4:23 p.m., Leo Mada via R-help wrote:
> > Dear R Users,
> >
> > Is this desired behaviour?
> > I presume it's a bug.
> >
2024 Sep 06
1
BUG: atan(1i) / 5 = NaN+Infi ?
On 2024-09-06 12:44 a.m., Richard O'Keefe wrote:
> I expect that atan(1i) = (0 + infinity i) and that atan(1i)/5 = (0 +
> infinity i)/5 = (0 + infinity i).
> Here's what I get in C:
> (0,1) = (0, 1)
> atan((0,1)) = (0, inf)
> atan((0,1))/5 = (0, inf)
>
> Note the difference between I*infinity = (0,1)*infinity =
> (0*infinity,1*infinity) = (NaN,infinity)
> and
2024 Sep 06
1
BUG: atan(1i) / 5 = NaN+Infi ?
>>>>> Richard O'Keefe
>>>>> on Fri, 6 Sep 2024 17:24:07 +1200 writes:
> The thing is that real*complex, complex*real, and complex/real are not
> "complex arithmetic" in the requisite sense.
> The complex numbers are a vector space over the reals,
Yes, but they _also_ are field (and as others have argued mathematically only
2024 Sep 06
1
BUG: atan(1i) / 5 = NaN+Infi ?
The thing is that real*complex, complex*real, and complex/real are not
"complex arithmetic"
in the requisite sense. The complex numbers are a vector space over
the reals, and
complex*real and real*complex are vector*scalar and scalar*vector.
For example, in the Ada programming language, we have
function "*" (Left, Right : Complex) return Complex;
function "*" (Left :
2024 Sep 05
2
BUG: atan(1i) / 5 = NaN+Infi ?
atan(1i) -> 0 + Inf i
complex(1/5) -> 0.2 + 0i
atan(1i) -> (0 + Inf i) * (0.2 + 0i)
-> 0*0.2 + 0*0i + Inf i * 0.2 + Inf i * 0i
infinity times zero is undefined
-> 0 + 0i + Inf i + NaN * i^2
-> 0 + 0i + Inf i - NaN
-> NaN + Inf i
I am not sure how complex arithmetic could arrive at another answer.
I advise against messing with infinities... use atan2() if you don't
2006 Mar 28
2
atan2(1,1i)
Hi
?atan2 says that atan2(y,x)=atan(y/x) for x and y numeric or complex
vectors.
Well, I would expect atan2(1,1i) to be equal to atan(-1i), but
> atan2(1,1i)
Error in atan2(y, x) : Non-numeric argument to mathematical function
> R.version
_
platform powerpc-apple-darwin8.5.0
arch powerpc
os darwin8.5.0
system powerpc, darwin8.5.0
2006 Mar 28
2
atan2(1,1i)
Hi
?atan2 says that atan2(y,x)=atan(y/x) for x and y numeric or complex
vectors.
Well, I would expect atan2(1,1i) to be equal to atan(-1i), but
> atan2(1,1i)
Error in atan2(y, x) : Non-numeric argument to mathematical function
> R.version
_
platform powerpc-apple-darwin8.5.0
arch powerpc
os darwin8.5.0
system powerpc, darwin8.5.0
2005 May 16
1
branch cuts of atan()
Hi
the following gave me a shock:
> atan(2)
[1] 1.107149
> atan(2+0i)
[1] -0.4636476+0i
>
or, perhaps more of a gotcha:
> atan(1.0001+0i)
[1] -0.7853482+0i
> atan(0.9999+0i)
[1] 0.7853482+0i
>
evidently atan()'s branch cuts aren't where I thought they were.
Where do I look for documentation on this?
--
Robin Hankin
Uncertainty Analyst
National
2004 Jan 21
2
derivative of atan(x) and similar functions
Dear R experts.
'D()' function recognizes some of the analitical functions, such as
sin, cos, etc. But I'd like to take analytical derivatives from asin,
atan etc. functions. Are there any R packages providing that features?
Thanks.
--
Timur.
1997 Apr 23
1
R-beta: Version 0.49 Released
The newest version of R for Unix (version 0.49) is now available
(or soon will be) from the following sites.
NORTH AMERICA:
http://lib.stat.cmu.edu/R/Alpha
EUROPE:
ftp://ftp.stat.math.ethz.ch/R/
ftp://statlab.uni-heidelberg.de/pub/mirrors/auckland/R/
JAPAN:
ftp://ftp.u-aizu.ac.jp/pub/lang/R/
NEW ZEALAND:
ftp://stat.auckland.ac.nz/pub/R/
Please
1997 Apr 23
1
R-beta: Version 0.49 Released
The newest version of R for Unix (version 0.49) is now available
(or soon will be) from the following sites.
NORTH AMERICA:
http://lib.stat.cmu.edu/R/Alpha
EUROPE:
ftp://ftp.stat.math.ethz.ch/R/
ftp://statlab.uni-heidelberg.de/pub/mirrors/auckland/R/
JAPAN:
ftp://ftp.u-aizu.ac.jp/pub/lang/R/
NEW ZEALAND:
ftp://stat.auckland.ac.nz/pub/R/
Please
1997 Apr 23
1
R-beta: Version 0.49 Released
The newest version of R for Unix (version 0.49) is now available
(or soon will be) from the following sites.
NORTH AMERICA:
http://lib.stat.cmu.edu/R/Alpha
EUROPE:
ftp://ftp.stat.math.ethz.ch/R/
ftp://statlab.uni-heidelberg.de/pub/mirrors/auckland/R/
JAPAN:
ftp://ftp.u-aizu.ac.jp/pub/lang/R/
NEW ZEALAND:
ftp://stat.auckland.ac.nz/pub/R/
Please
2011 Feb 25
0
R 2.12.2 is released
I've rolled up R-2.12.2.tar.gz a short while ago. This is an update release, which fixes a number of mostly minor issues, and one major issue in which complex arithmetic was being messed up on some compiler platform.
You can get it from
http://cran.r-project.org/src/base/R-2/R-2.12.2.tar.gz
or wait for it to be mirrored at a CRAN site nearer to you.
Binaries for various platforms will