Geodesic
A method of approximation by rational functions on the real line
Matematičeskie zametki, Tome 22 (1977) no. 3, pp. 375-380 
V. N. Rusak. A method of approximation by rational functions on the real line. Matematičeskie zametki, Tome 22 (1977) no. 3, pp. 375-380. http://geodesic.mathdoc.fr/item/MZM_1977_22_3_a6/
@article{MZM_1977_22_3_a6,
     author = {V. N. Rusak},
     title = {A~method of approximation by rational functions on the real line},
     journal = {Matemati\v{c}eskie zametki},
     pages = {375--380},
     year = {1977},
     volume = {22},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1977_22_3_a6/}
}
TY  - JOUR
AU  - V. N. Rusak
TI  - A method of approximation by rational functions on the real line
JO  - Matematičeskie zametki
PY  - 1977
SP  - 375
EP  - 380
VL  - 22
IS  - 3
UR  - http://geodesic.mathdoc.fr/item/MZM_1977_22_3_a6/
LA  - ru
ID  - MZM_1977_22_3_a6
ER  - 
%0 Journal Article
%A V. N. Rusak
%T A method of approximation by rational functions on the real line
%J Matematičeskie zametki
%D 1977
%P 375-380
%V 22
%N 3
%U http://geodesic.mathdoc.fr/item/MZM_1977_22_3_a6/
%G ru
%F MZM_1977_22_3_a6

Voir la notice de l'article provenant de la source Math-Net.Ru

For a given system of numbers $\{z_k\}_{k=1}^n$, $\operatorname{Im}z_k>0$, rational functions of order $4n-2$ are constructed which effect for a function $f(x)\in C_\infty$ an approximation of the same order as the best approximation by proper rational functions having poles at the points $\{z_k\}_{k=1}^n$ and $\{\overline z_k\}_{k=1}^n$.