Re: [ROOT] TTRAP and TGTRA

From: Elena Potrebenikova (potreben@sunhe.jinr.ru)
Date: Fri Jun 23 2000 - 10:26:09 MEST


Hello, Francois
Thank you very much for your message.

I have a business trip now.
I'll try to check what you say as soon as possible and let you know.

  With my best regards,
                                   Valery

-----Original Message-----
From: GENTIT Francois-Xavier DAPNIA <GENTIT@DAPNIA.CEA.FR>
To: 'roottalk@root.cern.ch' <roottalk@pcroot.cern.ch>
Date: 22 ÉÀÎÑ 2000 Ç. 17:47
Subject: [ROOT] TTRAP and TGTRA


>  Dear authors of ROOT,
>  I feel uncomfortable when I compare the code of TTRAP::SetPointss() with
>the one of TGTRA::SetPoints(). As I understand, a TGTRA must become a TTRAP
>when the angle "twist" is set to 0. A first look at the code of the 2
>routines show that it is not the case. A second look indicates that may be
>it is not wrong, because the author of TTRAP::Setpoints() look at the angle
>theta from the middle in z of the shape, but the author of
>TGTRA::SetPoints() look at the angle theta from the bottom of the shape.
>Hence the appearance of factors 2 in the code of TGTRA::SetPoints().
>  But what really worries me is the fact that in TTRAP::SetPoints()
>Tan(theta) appears everywhere, and in the code of TGTRA::SetPoints()
>Sin(theta) appears everywhere.
>  I do not see how this difference in the views of the presumably different
>authors of the 2 methods could change a Tan into a Sin ?
>  Could a specialist of this part of ROOT have a look at it ?
>  Thanks very much.
>
>          F.X. Gentit
>          DAPNIA/SPP CEN Saclay
>          tel : 01 69 08 30 38     fax : 01 69 08 64 28
>          web : http://home.cern.ch/~gentit/
>
>



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