//
//Fit_P_RTPC.h  v3.0 
//This file makes the c++ subrutine can be used by c or fortran code
#ifndef _Fit_P_RTPC_
#define _Fit_P_RTPC_

#ifdef __cplusplus
extern "C"
{
#endif

/*------------------------------------------------------------------------\
Function name: double Threshold_P(double z0_mm,double theta0_rad)
calculate the momentum threshold using z0,theta0.

Input parameters:
	z0_mm:             the vertex position in mm 
	theta0_rad:         the theta angle in rad at r=0(the vertex)
OutPut: Momentum in Mev
\------------------------------------------------------------------------*/
  double Threshold_P(double z0_mm,double theta0_rad);

/*------------------------------------------------------------------------\
Function name: double Fit_P_by_R(double r_mm,double z0_mm,double theta0_deg, int dvcs_cur)
Input parameters:
	r_mm:        the raidus of the trajectory,in unit mm
	z0_mm:       the vertex position in mm
	theta0_deg:  the theta angle in degree at r=0(the vertex)
	dvcs_cur:    B field solinoid current, accepte 450 or 534
return: >0: total Momentum in MeV/c
	<0: this map doesn't work for the given r,z,theta
\------------------------------------------------------------------------*/

double Fit_P_by_R(double r_mm,double z0_mm,double theta0_deg, int dvcs_cur);

/*------------------------------------------------------------------------\
Function: int DoPCorr(double r_mm,double z0_mm,double theta0_rad, int dvcs_cur, 
                      double &p_total_mev)
Input parameters:
	r_mm:        the raidus of the trajectory,in unit mm
	z0_mm:       the vertex position in mm 
	theta0_rad:  the theta angle in radians  at r=0(the vertex)
	dvcs_cur:    B field solinoid current, accepte 450 or 534
OutPut: p_total_mev
		>0: total Momentum in MeV/c
		<0: this map doesn't work for the given r,z,theta
return: 0	no error. 
       	-1	error occurs!
\------------------------------------------------------------------------*/
int DoPCorr(double r_mm,double z0_mm,double theta0_rad, int dvcs_cur, double &p_total_mev);

#ifdef __cplusplus
}
#endif
#endif