///////////////////////////////////////////////////
#include <Riostream.h>
-
-#include "AliCallf77.h"
#include "AliMUON.h"
#include "AliMUONTrackParam.h"
#include "AliMUONChamber.h"
#include "AliRun.h"
#include "AliMagF.h"
+#include "AliLog.h"
ClassImp(AliMUONTrackParam) // Class implementation in ROOT context
- // A few calls in Fortran or from Fortran (extrap.F).
- // Needed, instead of calls to Geant subroutines,
- // because double precision is necessary for track fit converging with Minuit.
- // The "extrap" functions should be translated into C++ ????
-#ifndef WIN32
-# define extrap_onestep_helix extrap_onestep_helix_
-# define extrap_onestep_helix3 extrap_onestep_helix3_
-# define extrap_onestep_rungekutta extrap_onestep_rungekutta_
-# define gufld_double gufld_double_
-#else
-# define extrap_onestep_helix EXTRAP_ONESTEP_HELIX
-# define extrap_onestep_helix3 EXTRAP_ONESTEP_HELIX3
-# define extrap_onestep_rungekutta EXTRAP_ONESTEP_RUNGEKUTTA
-# define gufld_double GUFLD_DOUBLE
-#endif
-
-extern "C" {
- void type_of_call extrap_onestep_helix
- (Double_t &Charge, Double_t &StepLength, Double_t *VGeant3, Double_t *VGeant3New);
-
- void type_of_call extrap_onestep_helix3
- (Double_t &Field, Double_t &StepLength, Double_t *VGeant3, Double_t *VGeant3New);
-
- void type_of_call extrap_onestep_rungekutta
- (Double_t &Charge, Double_t &StepLength, Double_t *VGeant3, Double_t *VGeant3New);
-
- void type_of_call gufld_double(Double_t *Position, Double_t *Field) {
- // interface to "gAlice->Field()->Field" for arguments in double precision
- Float_t x[3], b[3];
- x[0] = Position[0]; x[1] = Position[1]; x[2] = Position[2];
- gAlice->Field()->Field(x, b);
- Field[0] = b[0]; Field[1] = b[1]; Field[2] = b[2];
- }
-}
-
//_________________________________________________________________________
AliMUONTrackParam::AliMUONTrackParam()
: TObject()
(stepNumber < maxStepNumber)) {
stepNumber++;
// Option for switching between helix and Runge-Kutta ????
- // extrap_onestep_rungekutta(chargeExtrap, stepLength, vGeant3, vGeant3New);
- extrap_onestep_helix(chargeExtrap, stepLength, vGeant3, vGeant3New);
+ //ExtrapOneStepRungekutta(chargeExtrap, stepLength, vGeant3, vGeant3New);
+ ExtrapOneStepHelix(chargeExtrap, stepLength, vGeant3, vGeant3New);
if ((-forwardBackward * (vGeant3New[2] - Z)) > 0.0) break; // one is beyond Z spectro. z<0
// better use TArray ????
for (iGeant3 = 0; iGeant3 < 7; iGeant3++)
if ((z1 > this->fZ) && (z2 > this->fZ)) {i1 = 0; i2 = 1;}
else if ((z1 < this->fZ) && (z2 < this->fZ)) {i1 = 1; i2 = 0;}
else {
- cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
- cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
- ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
+ AliError(Form("Starting Z (%f) in between z1 (%f) and z2 (%f) of station(0..)%d",this->fZ,z1,z2,Station));
+// cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
+// cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
+// ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
}
extZ[i1] = z1;
extZ[i2] = z2;
}
//__________________________________________________________________________
-void AliMUONTrackParam::ExtrapToVertex()
+void AliMUONTrackParam::ExtrapToVertex(Double_t xVtx, Double_t yVtx, Double_t zVtx)
{
// Extrapolation to the vertex.
// Returns the track parameters resulting from the extrapolation,
// Extrapolates track parameters upstream to the "Z" end of the front absorber
ExtrapToZ(zAbsorber); // !!!
// Makes Branson correction (multiple scattering + energy loss)
- BransonCorrection();
+ BransonCorrection(xVtx,yVtx,zVtx);
// Makes a simple magnetic field correction through the absorber
FieldCorrection(zAbsorber);
}
// fZ= 0;
// }
-void AliMUONTrackParam::BransonCorrection()
+void AliMUONTrackParam::BransonCorrection(Double_t xVtx,Double_t yVtx,Double_t zVtx)
{
// Branson correction of track parameters
// the entry parameters have to be calculated at the end of the absorber
// Would it be possible to calculate all that from Geant configuration ????
// and to get the Branson parameters from a function in ABSO module ????
// with an eventual contribution from other detectors like START ????
+ //change to take into account the vertex postition (real, reconstruct,....)
+
Double_t zBP, xBP, yBP;
Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
Int_t sign;
pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
sign = 1;
- if (fInverseBendingMomentum < 0) sign = -1;
- pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro (z<0)
- pX = pZ * fNonBendingSlope;
- pY = pZ * fBendingSlope;
+ if (fInverseBendingMomentum < 0) sign = -1;
+ pZ = Pz();
+ pX = Px();
+ pY = Py();
pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
xEndAbsorber = fNonBendingCoor;
yEndAbsorber = fBendingCoor;
// new parameters after Branson and energy loss corrections
// Float_t zSmear = zBP - gRandom->Gaus(0.,2.); // !!! possible smearing of Z vertex position
- Float_t zSmear = zBP;
+
+ Float_t zSmear = zBP ;
- pZ = pTotal * zSmear / TMath::Sqrt(xBP * xBP + yBP * yBP + zSmear * zSmear);
- pX = pZ * xBP / zSmear;
- pY = pZ * yBP / zSmear;
+ pZ = pTotal * (zSmear-zVtx) / TMath::Sqrt((xBP-xVtx) * (xBP-xVtx) + (yBP-yVtx) * (yBP-yVtx) +( zSmear-zVtx) * (zSmear-zVtx) );
+ pX = pZ * (xBP - xVtx)/ (zSmear-zVtx);
+ pY = pZ * (yBP - yVtx) / (zSmear-zVtx);
fBendingSlope = pY / pZ;
fNonBendingSlope = pX / pZ;
// vertex position at (0,0,0)
// should be taken from vertex measurement ???
- fBendingCoor = 0.0;
- fNonBendingCoor = 0;
- fZ= 0;
+
+ fBendingCoor = xVtx;
+ fNonBendingCoor = yVtx;
+ fZ= zVtx;
+
}
//__________________________________________________________________________
pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
c = TMath::Sign(1.0,fInverseBendingMomentum); // particle charge
- pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
- pX = pZ * fNonBendingSlope;
- pY = pZ * fBendingSlope;
+ pZ = Pz();
+ pX = Px();
+ pY = Py();
pT = TMath::Sqrt(pX*pX+pY*pY);
if (TMath::Abs(pZ) <= 0) return;
fInverseBendingMomentum = c / TMath::Sqrt(pYNew*pYNew+pZ*pZ);
}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::Px()
+{
+ // return px from track paramaters
+ Double_t pYZ, pZ, pX;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ pX = pZ * fNonBendingSlope;
+ return pX;
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::Py()
+{
+ // return px from track paramaters
+ Double_t pYZ, pZ, pY;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ pY = pZ * fBendingSlope;
+ return pY;
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::Pz()
+{
+ // return px from track paramaters
+ Double_t pYZ, pZ;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ return pZ;
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::P()
+{
+ // return p from track paramaters
+ Double_t pYZ, pZ, p;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ p = TMath::Abs(pZ) *
+ TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope + fNonBendingSlope * fNonBendingSlope);
+ return p;
+
+}
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapOneStepHelix(Double_t charge, Double_t step,
+ Double_t *vect, Double_t *vout)
+{
+// ******************************************************************
+// * *
+// * Performs the tracking of one step in a magnetic field *
+// * The trajectory is assumed to be a helix in a constant field *
+// * taken at the mid point of the step. *
+// * Parameters: *
+// * input *
+// * STEP =arc length of the step asked *
+// * VECT =input vector (position,direction cos and momentum) *
+// * CHARGE= electric charge of the particle *
+// * output *
+// * VOUT = same as VECT after completion of the step *
+// * *
+// * ==>Called by : <USER>, GUSWIM *
+// * Author m.hansroul ********* *
+// * modified s.egli, s.v.levonian *
+// * modified v.perevoztchikov
+// * *
+// ******************************************************************
+//
+
+// modif: everything in double precision
+
+ Double_t xyz[3], h[4], hxp[3];
+ Double_t h2xy, hp, rho, tet;
+ Double_t sint, sintt, tsint, cos1t;
+ Double_t f1, f2, f3, f4, f5, f6;
+
+ const Int_t ix = 0;
+ const Int_t iy = 1;
+ const Int_t iz = 2;
+ const Int_t ipx = 3;
+ const Int_t ipy = 4;
+ const Int_t ipz = 5;
+ const Int_t ipp = 6;
+
+ const Double_t ec = 2.9979251e-4;
+ //
+ // ------------------------------------------------------------------
+ //
+ // units are kgauss,centimeters,gev/c
+ //
+ vout[ipp] = vect[ipp];
+ if (TMath::Abs(charge) < 0.00001) {
+ for (Int_t i = 0; i < 3; i++) {
+ vout[i] = vect[i] + step * vect[i+3];
+ vout[i+3] = vect[i+3];
+ }
+ return;
+ }
+ xyz[0] = vect[ix] + 0.5 * step * vect[ipx];
+ xyz[1] = vect[iy] + 0.5 * step * vect[ipy];
+ xyz[2] = vect[iz] + 0.5 * step * vect[ipz];
+
+ //cmodif: call gufld (xyz, h) changed into:
+ GetField (xyz, h);
+
+ h2xy = h[0]*h[0] + h[1]*h[1];
+ h[3] = h[2]*h[2]+ h2xy;
+ if (h[3] < 1.e-12) {
+ for (Int_t i = 0; i < 3; i++) {
+ vout[i] = vect[i] + step * vect[i+3];
+ vout[i+3] = vect[i+3];
+ }
+ return;
+ }
+ if (h2xy < 1.e-12*h[3]) {
+ ExtrapOneStepHelix3(charge*h[2], step, vect, vout);
+ return;
+ }
+ h[3] = TMath::Sqrt(h[3]);
+ h[0] /= h[3];
+ h[1] /= h[3];
+ h[2] /= h[3];
+ h[3] *= ec;
+
+ hxp[0] = h[1]*vect[ipz] - h[2]*vect[ipy];
+ hxp[1] = h[2]*vect[ipx] - h[0]*vect[ipz];
+ hxp[2] = h[0]*vect[ipy] - h[1]*vect[ipx];
+
+ hp = h[0]*vect[ipx] + h[1]*vect[ipy] + h[2]*vect[ipz];
+
+ rho = -charge*h[3]/vect[ipp];
+ tet = rho * step;
+
+ if (TMath::Abs(tet) > 0.15) {
+ sint = TMath::Sin(tet);
+ sintt = (sint/tet);
+ tsint = (tet-sint)/tet;
+ cos1t = 2.*(TMath::Sin(0.5*tet))*(TMath::Sin(0.5*tet))/tet;
+ } else {
+ tsint = tet*tet/36.;
+ sintt = (1. - tsint);
+ sint = tet*sintt;
+ cos1t = 0.5*tet;
+ }
+
+ f1 = step * sintt;
+ f2 = step * cos1t;
+ f3 = step * tsint * hp;
+ f4 = -tet*cos1t;
+ f5 = sint;
+ f6 = tet * cos1t * hp;
+
+ vout[ix] = vect[ix] + f1*vect[ipx] + f2*hxp[0] + f3*h[0];
+ vout[iy] = vect[iy] + f1*vect[ipy] + f2*hxp[1] + f3*h[1];
+ vout[iz] = vect[iz] + f1*vect[ipz] + f2*hxp[2] + f3*h[2];
+
+ vout[ipx] = vect[ipx] + f4*vect[ipx] + f5*hxp[0] + f6*h[0];
+ vout[ipy] = vect[ipy] + f4*vect[ipy] + f5*hxp[1] + f6*h[1];
+ vout[ipz] = vect[ipz] + f4*vect[ipz] + f5*hxp[2] + f6*h[2];
+
+ return;
+}
+
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapOneStepHelix3(Double_t field, Double_t step,
+ Double_t *vect, Double_t *vout)
+{
+//
+// ******************************************************************
+// * *
+// * Tracking routine in a constant field oriented *
+// * along axis 3 *
+// * Tracking is performed with a conventional *
+// * helix step method *
+// * *
+// * ==>Called by : <USER>, GUSWIM *
+// * Authors R.Brun, M.Hansroul ********* *
+// * Rewritten V.Perevoztchikov
+// * *
+// ******************************************************************
+//
+
+ Double_t hxp[3];
+ Double_t h4, hp, rho, tet;
+ Double_t sint, sintt, tsint, cos1t;
+ Double_t f1, f2, f3, f4, f5, f6;
+
+ const Int_t ix = 0;
+ const Int_t iy = 1;
+ const Int_t iz = 2;
+ const Int_t ipx = 3;
+ const Int_t ipy = 4;
+ const Int_t ipz = 5;
+ const Int_t ipp = 6;
+
+ const Double_t ec = 2.9979251e-4;
+
+//
+// ------------------------------------------------------------------
+//
+// units are kgauss,centimeters,gev/c
+//
+ vout[ipp] = vect[ipp];
+ h4 = field * ec;
+
+ hxp[0] = - vect[ipy];
+ hxp[1] = + vect[ipx];
+
+ hp = vect[ipz];
+
+ rho = -h4/vect[ipp];
+ tet = rho * step;
+ if (TMath::Abs(tet) > 0.15) {
+ sint = TMath::Sin(tet);
+ sintt = (sint/tet);
+ tsint = (tet-sint)/tet;
+ cos1t = 2.* TMath::Sin(0.5*tet) * TMath::Sin(0.5*tet)/tet;
+ } else {
+ tsint = tet*tet/36.;
+ sintt = (1. - tsint);
+ sint = tet*sintt;
+ cos1t = 0.5*tet;
+ }
+
+ f1 = step * sintt;
+ f2 = step * cos1t;
+ f3 = step * tsint * hp;
+ f4 = -tet*cos1t;
+ f5 = sint;
+ f6 = tet * cos1t * hp;
+
+ vout[ix] = vect[ix] + f1*vect[ipx] + f2*hxp[0];
+ vout[iy] = vect[iy] + f1*vect[ipy] + f2*hxp[1];
+ vout[iz] = vect[iz] + f1*vect[ipz] + f3;
+
+ vout[ipx] = vect[ipx] + f4*vect[ipx] + f5*hxp[0];
+ vout[ipy] = vect[ipy] + f4*vect[ipy] + f5*hxp[1];
+ vout[ipz] = vect[ipz] + f4*vect[ipz] + f6;
+
+ return;
+}
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapOneStepRungekutta(Double_t charge, Double_t step,
+ Double_t* vect, Double_t* vout)
+{
+//
+// ******************************************************************
+// * *
+// * Runge-Kutta method for tracking a particle through a magnetic *
+// * field. Uses Nystroem algorithm (See Handbook Nat. Bur. of *
+// * Standards, procedure 25.5.20) *
+// * *
+// * Input parameters *
+// * CHARGE Particle charge *
+// * STEP Step size *
+// * VECT Initial co-ords,direction cosines,momentum *
+// * Output parameters *
+// * VOUT Output co-ords,direction cosines,momentum *
+// * User routine called *
+// * CALL GUFLD(X,F) *
+// * *
+// * ==>Called by : <USER>, GUSWIM *
+// * Authors R.Brun, M.Hansroul ********* *
+// * V.Perevoztchikov (CUT STEP implementation) *
+// * *
+// * *
+// ******************************************************************
+//
+
+ Double_t h2, h4, f[4];
+ Double_t xyzt[3], a, b, c, ph,ph2;
+ Double_t secxs[4],secys[4],seczs[4],hxp[3];
+ Double_t g1, g2, g3, g4, g5, g6, ang2, dxt, dyt, dzt;
+ Double_t est, at, bt, ct, cba;
+ Double_t f1, f2, f3, f4, rho, tet, hnorm, hp, rho1, sint, cost;
+
+ Double_t x;
+ Double_t y;
+ Double_t z;
+
+ Double_t xt;
+ Double_t yt;
+ Double_t zt;
+
+ Double_t maxit = 1992;
+ Double_t maxcut = 11;
+
+ const Double_t dlt = 1e-4;
+ const Double_t dlt32 = dlt/32.;
+ const Double_t third = 1./3.;
+ const Double_t half = 0.5;
+ const Double_t ec = 2.9979251e-4;
+
+ const Double_t pisqua = 9.86960440109;
+ const Int_t ix = 0;
+ const Int_t iy = 1;
+ const Int_t iz = 2;
+ const Int_t ipx = 3;
+ const Int_t ipy = 4;
+ const Int_t ipz = 5;
+
+ // *.
+ // *. ------------------------------------------------------------------
+ // *.
+ // * this constant is for units cm,gev/c and kgauss
+ // *
+ Int_t iter = 0;
+ Int_t ncut = 0;
+ for(Int_t j = 0; j < 7; j++)
+ vout[j] = vect[j];
+
+ Double_t pinv = ec * charge / vect[6];
+ Double_t tl = 0.;
+ Double_t h = step;
+ Double_t rest;
+
+
+ do {
+ rest = step - tl;
+ if (TMath::Abs(h) > TMath::Abs(rest)) h = rest;
+ //cmodif: call gufld(vout,f) changed into:
+
+ GetField(vout,f);
+
+ // *
+ // * start of integration
+ // *
+ x = vout[0];
+ y = vout[1];
+ z = vout[2];
+ a = vout[3];
+ b = vout[4];
+ c = vout[5];
+
+ h2 = half * h;
+ h4 = half * h2;
+ ph = pinv * h;
+ ph2 = half * ph;
+ secxs[0] = (b * f[2] - c * f[1]) * ph2;
+ secys[0] = (c * f[0] - a * f[2]) * ph2;
+ seczs[0] = (a * f[1] - b * f[0]) * ph2;
+ ang2 = (secxs[0]*secxs[0] + secys[0]*secys[0] + seczs[0]*seczs[0]);
+ if (ang2 > pisqua) break;
+
+ dxt = h2 * a + h4 * secxs[0];
+ dyt = h2 * b + h4 * secys[0];
+ dzt = h2 * c + h4 * seczs[0];
+ xt = x + dxt;
+ yt = y + dyt;
+ zt = z + dzt;
+ // *
+ // * second intermediate point
+ // *
+
+ est = TMath::Abs(dxt) + TMath::Abs(dyt) + TMath::Abs(dzt);
+ if (est > h) {
+ if (ncut++ > maxcut) break;
+ h *= half;
+ continue;
+ }
+
+ xyzt[0] = xt;
+ xyzt[1] = yt;
+ xyzt[2] = zt;
+
+ //cmodif: call gufld(xyzt,f) changed into:
+ GetField(xyzt,f);
+
+ at = a + secxs[0];
+ bt = b + secys[0];
+ ct = c + seczs[0];
+
+ secxs[1] = (bt * f[2] - ct * f[1]) * ph2;
+ secys[1] = (ct * f[0] - at * f[2]) * ph2;
+ seczs[1] = (at * f[1] - bt * f[0]) * ph2;
+ at = a + secxs[1];
+ bt = b + secys[1];
+ ct = c + seczs[1];
+ secxs[2] = (bt * f[2] - ct * f[1]) * ph2;
+ secys[2] = (ct * f[0] - at * f[2]) * ph2;
+ seczs[2] = (at * f[1] - bt * f[0]) * ph2;
+ dxt = h * (a + secxs[2]);
+ dyt = h * (b + secys[2]);
+ dzt = h * (c + seczs[2]);
+ xt = x + dxt;
+ yt = y + dyt;
+ zt = z + dzt;
+ at = a + 2.*secxs[2];
+ bt = b + 2.*secys[2];
+ ct = c + 2.*seczs[2];
+
+ est = TMath::Abs(dxt)+TMath::Abs(dyt)+TMath::Abs(dzt);
+ if (est > 2.*TMath::Abs(h)) {
+ if (ncut++ > maxcut) break;
+ h *= half;
+ continue;
+ }
+
+ xyzt[0] = xt;
+ xyzt[1] = yt;
+ xyzt[2] = zt;
+
+ //cmodif: call gufld(xyzt,f) changed into:
+ GetField(xyzt,f);
+
+ z = z + (c + (seczs[0] + seczs[1] + seczs[2]) * third) * h;
+ y = y + (b + (secys[0] + secys[1] + secys[2]) * third) * h;
+ x = x + (a + (secxs[0] + secxs[1] + secxs[2]) * third) * h;
+
+ secxs[3] = (bt*f[2] - ct*f[1])* ph2;
+ secys[3] = (ct*f[0] - at*f[2])* ph2;
+ seczs[3] = (at*f[1] - bt*f[0])* ph2;
+ a = a+(secxs[0]+secxs[3]+2. * (secxs[1]+secxs[2])) * third;
+ b = b+(secys[0]+secys[3]+2. * (secys[1]+secys[2])) * third;
+ c = c+(seczs[0]+seczs[3]+2. * (seczs[1]+seczs[2])) * third;
+
+ est = TMath::Abs(secxs[0]+secxs[3] - (secxs[1]+secxs[2]))
+ + TMath::Abs(secys[0]+secys[3] - (secys[1]+secys[2]))
+ + TMath::Abs(seczs[0]+seczs[3] - (seczs[1]+seczs[2]));
+
+ if (est > dlt && TMath::Abs(h) > 1.e-4) {
+ if (ncut++ > maxcut) break;
+ h *= half;
+ continue;
+ }
+
+ ncut = 0;
+ // * if too many iterations, go to helix
+ if (iter++ > maxit) break;
+
+ tl += h;
+ if (est < dlt32)
+ h *= 2.;
+ cba = 1./ TMath::Sqrt(a*a + b*b + c*c);
+ vout[0] = x;
+ vout[1] = y;
+ vout[2] = z;
+ vout[3] = cba*a;
+ vout[4] = cba*b;
+ vout[5] = cba*c;
+ rest = step - tl;
+ if (step < 0.) rest = -rest;
+ if (rest < 1.e-5*TMath::Abs(step)) return;
+
+ } while(1);
+
+ // angle too big, use helix
+
+ f1 = f[0];
+ f2 = f[1];
+ f3 = f[2];
+ f4 = TMath::Sqrt(f1*f1+f2*f2+f3*f3);
+ rho = -f4*pinv;
+ tet = rho * step;
+
+ hnorm = 1./f4;
+ f1 = f1*hnorm;
+ f2 = f2*hnorm;
+ f3 = f3*hnorm;
+
+ hxp[0] = f2*vect[ipz] - f3*vect[ipy];
+ hxp[1] = f3*vect[ipx] - f1*vect[ipz];
+ hxp[2] = f1*vect[ipy] - f2*vect[ipx];
+
+ hp = f1*vect[ipx] + f2*vect[ipy] + f3*vect[ipz];
+
+ rho1 = 1./rho;
+ sint = TMath::Sin(tet);
+ cost = 2.*TMath::Sin(half*tet)*TMath::Sin(half*tet);
+
+ g1 = sint*rho1;
+ g2 = cost*rho1;
+ g3 = (tet-sint) * hp*rho1;
+ g4 = -cost;
+ g5 = sint;
+ g6 = cost * hp;
+
+ vout[ix] = vect[ix] + g1*vect[ipx] + g2*hxp[0] + g3*f1;
+ vout[iy] = vect[iy] + g1*vect[ipy] + g2*hxp[1] + g3*f2;
+ vout[iz] = vect[iz] + g1*vect[ipz] + g2*hxp[2] + g3*f3;
+
+ vout[ipx] = vect[ipx] + g4*vect[ipx] + g5*hxp[0] + g6*f1;
+ vout[ipy] = vect[ipy] + g4*vect[ipy] + g5*hxp[1] + g6*f2;
+ vout[ipz] = vect[ipz] + g4*vect[ipz] + g5*hxp[2] + g6*f3;
+
+ return;
+}
+//___________________________________________________________
+ void AliMUONTrackParam::GetField(Double_t *Position, Double_t *Field)
+{
+ // interface to "gAlice->Field()->Field" for arguments in double precision
+
+ Float_t x[3], b[3];
+
+ x[0] = Position[0]; x[1] = Position[1]; x[2] = Position[2];
+
+ gAlice->Field()->Field(x, b);
+ Field[0] = b[0]; Field[1] = b[1]; Field[2] = b[2];
+
+ return;
+ }
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff