error in computing atanh
1 回表示 (過去 30 日間)
古いコメントを表示
Francisco Peñuñuri
2021 年 2 月 13 日
編集済み: Francisco Peñuñuri
2021 年 2 月 13 日
When computing atanh(3.1) in R2018.a and R2020.a the complex part has positive sign.
When computing in fortran (and Mathematica) the result is negative.
0 件のコメント
採用された回答
David Goodmanson
2021 年 2 月 13 日
編集済み: David Goodmanson
2021 年 2 月 13 日
Hello Francisco,
The imaginary part is i*pi/2, so the two answers are a+i*pi/2 and a-i*pi/2, where a is real. Both answers are equally valid, so unless an answer is violating some prearranged standard set by the particular software invoked, there is not an error. Note that
tanh(a+i*b) = tanh(a+i*b+i*n*pi)
so there is an ambiguity modulo i*pi in the atahh function..
3 件のコメント
John D'Errico
2021 年 2 月 13 日
But there is no international standards commission that decides which is the principal branch to take on some multi-valued result. And while it seems pretty standard to take the POSITIVE branch for a sqrt, so it may have seemed just as logical to take the positive branch here.
The result is valid and non-unique. You cannot say more than that.
その他の回答 (0 件)
参考
カテゴリ
Help Center および File Exchange で Logical についてさらに検索
製品
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!