atan2(0,0) is not undefined (NaN)

19 visualizaciones (últimos 30 días)
Daven Gooden
Daven Gooden el 11 de Ag. de 2020
Comentada: hosein Javan el 11 de Ag. de 2020
I'm using MATLAB R2020a Home Edition on a Windows® machine. I have a need to calculate atan2(0,0) which, if I am correct should result in NaN (undefined). The answer I get is zero. Is this not bug in the underline algorithm for computation of atan2()?
Thank you in advance.

Respuesta aceptada

Star Strider
Star Strider el 11 de Ag. de 2020
That is defined in the IEEE Compliance section of the atan2 documentation.
The result also isd not completely standardised. See the section in the Wikipedia article on Atan2 on Realizations of the function in common computer languages.
  2 comentarios
Daven Gooden
Daven Gooden el 11 de Ag. de 2020
Editada: Daven Gooden el 11 de Ag. de 2020
Star Strider thank you for replying! I did not realize the C language implementation of atan2(0,0) == 0 is what MATLAB is using. This is not what I want, but is good to know. I can compensate for that.
Star Strider
Star Strider el 11 de Ag. de 2020
As always, my pleasure!
MATLAB began as a FORTRAN implementation, later switching to C.

Iniciar sesión para comentar.

Más respuestas (2)

James Tursa
James Tursa el 11 de Ag. de 2020
  1 comentario
Daven Gooden
Daven Gooden el 11 de Ag. de 2020
James thanks for your reply. I now see the "IEEE Compliance" section within the help documentation. That is good information to keep in mind!

Iniciar sesión para comentar.


hosein Javan
hosein Javan el 11 de Ag. de 2020
it is not a bug. although in analytic math it is undefined, the trigonometric functions are usually calculated by their taylor series expansion on numerical softwares. no doubt it results zero. however when you try very small values, it is still correct:
atan2(1e-301,1e-301)*180/pi
ans =
45
  2 comentarios
Daven Gooden
Daven Gooden el 11 de Ag. de 2020
Thanks Hosein! I appreciate your willingness to help. Your input is very helpful.
hosein Javan
hosein Javan el 11 de Ag. de 2020
don't mention it.

Iniciar sesión para comentar.

Categorías

Más información sobre MATLAB en Help Center y File Exchange.

Productos


Versión

R2020a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by