Thank you very much. There was a misunderstanding because of my poor English. In German the inverse formula is called Umkehrfunktion. In the book Bronstein Semendjajew Taschenbuch der Mathematik is a clear definition so there will be no more such poor questions.
Thank you very much. There was a misunderstanding because of my poor English. In German the inverse formula is called Umkehrfunktion. In the book Bronstein Semendjajew Taschenbuch der Mathematik is a clear definition so there will be no more such poor questions.