Hello,
while trying to use TGeom (TNode,...) in AliRoot, I noticed a pb which
can be seen in this basic macro:
{
gROOT->LoadMacro("loadlibs.C");
loadlibs();
TFile *file = new TFile("galice.root");
if (!gAlice)
{
gAlice = (AliRun*)file->Get("gAlice");
if (gAlice) printf("AliRun object found on file\n");
if (!gAlice) gAlice = new AliRun("gAlice","Alice test program");
}
char namech[10];
char name[10];
sprintf(name,"SLAT_N%d",slatnum);
// Converting local -> master
Float_t local[3],local2[3], master[3];
local[0] = x1;
local[1] = y1;
local[2] = 0;
TNode *node = gAlice->GetGeometry()->GetNode(name);
node->UpdateMatrix();
node->Local2Master(local,master);
cout<<"local "<<local[0]<<" "<<local[1]<<" "<<local[2] << endl;
cout<<" master "<<master[0]<<" "<<master[1]<<" "<<master[2]<<endl;
node->UpdateMatrix();
node->Master2Local(master,local2);
cout<<"local2 "<<local2[0]<<" "<<local2[1]<<" "<<local2[2] << endl;
}
which give this outpout (this is not normal since we have to found the
same starting and ending values...):
local 10 3 0
master 75.7508 68.2644 986
local2 9.73511 3.77195 1.63918e-15
(int)1085958144
Maybe the same problem was describe in this ROOT Talk, but this question
had no answear:
From: Volker Hejny (V.Hejny@fz-juelich.de)
Date: Tue Aug 28 2001 - 08:30:19 MEST
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Hi all,
I tried to use TGeometry and played with the transformation
function Master2Local and Local2Master. While the latter
worked properly, the other did not what I assumed. On
closer look I found, that the same matrix is used as
in Local2Master. Instead the transposed should be used.
Best regards,
Volker
--
Dr. Volker Hejny Tel: 02461/616853
**
Institut f. Kernphysik Fax: 02461/613930 **
---------------------------------------------------------------- ** **
---
Forschungszentrum Juelich GmbH, D-52425 Juelich **
Thanks a lot in advance,
Eric
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