BFieldCache Class Reference

BFieldCache.h. More...

#include <BFieldCache.h>

Collaboration diagram for BFieldCache:

Public Member Functions
	BFieldCache ()=default
void	invalidate ()
void	setRange (double zmin, double zmax, double rmin, double rmax, double phimin, double phimax)
void	setField (const CxxUtils::vec< double, 8 > &field1, const CxxUtils::vec< double, 8 > &field2, const CxxUtils::vec< double, 8 > &field3)
void	setBscale (double bscale)
float	bscale () const
bool	inside (double z, double r, double phi) const
void	getB (const double *ATH_RESTRICT xyz, double r, double phi, double *ATH_RESTRICT B, double *ATH_RESTRICT deriv=nullptr) const

Private Attributes
double	m_zmin = 0.0
double	m_zmax = 0.0
double	m_rmin = 0.0
double	m_rmax = 0.0
double	m_phimin = 0.0
double	m_phimax = -1.0
double	m_invz
double	m_invr
double	m_invphi
double	m_scale
double	m_field [3][8]

Detailed Description

BFieldCache.h.

Cache of one bin of the magnetic field map. Defined by ranges in z, r, phi, and the B vectors at the 8 corners of the "bin".

Masahiro Morii, Harvard University

AthenaMT : RD Schaffer , Christos Anastopoulos

Definition at line 24 of file BFieldCache.h.

Constructor & Destructor Documentation

BFieldCache()

BFieldCache::BFieldCache ( )

default

Member Function Documentation

bscale()

float BFieldCache::bscale

(

)

const

getB()

void BFieldCache::getB	(	const double *ATH_RESTRICT	xyz,
		double	r,
		double	phi,
		double *ATH_RESTRICT	B,
		double *ATH_RESTRICT	deriv = nullptr
	)		const

Definition at line 99 of file BFieldCache.cxx.

                                                    {
 
  const double x = xyz[0];
  const double y = xyz[1];
  const double z = xyz[2];
 
  // make sure phi is inside [m_phimin,m_phimax]
  if (phi < m_phimin) {
    phi += 2 * M_PI;
  }
  // fractional position inside this bin
  const double fz = (z - m_zmin) * m_invz;
  const double gz = 1.0 - fz;
  const double fr = (r - m_rmin) * m_invr;
  const double gr = 1.0 - fr;
  const double fphi = (phi - m_phimin) * m_invphi;
  const double gphi = 1.0 - fphi;
 
  // get B in Z,r,phi
  double Bzrphi[4];
  getBzrphi(Bzrphi, m_field, fz, gz, fr, gr, fphi, gphi, m_scale);
  // convert (Bz,Br,Bphi) to (Bx,By,Bz)
  double invr;
  double c;
  double s;
  if (r > 0.0) {
    invr = 1.0 / r;
    c = x * invr;
    s = y * invr;
  } else {
    invr = 0.0;
    c = cos(m_phimin);
    s = sin(m_phimin);
  }
  B[0] = Bzrphi[1] * c - Bzrphi[2] * s;
  B[1] = Bzrphi[1] * s + Bzrphi[2] * c;
  B[2] = Bzrphi[0];
 
  // compute field derivatives if requested
  if (deriv) {
    const double sz = m_scale * m_invz;
    const double sr = m_scale * m_invr;
    const double sphi = m_scale * m_invphi;
 
    std::array<double, 3> dBdz{};
    std::array<double, 3> dBdr{};
    std::array<double, 3> dBdphi{};
 
    for (int j = 0; j < 3; ++j) { // Bz, Br, Bphi components
      const double* field = m_field[j];
      dBdz[j] =
        sz *
        (gr * (gphi * (field[2] - field[0]) + fphi * (field[6] - field[4])) +
         fr * (gphi * (field[3] - field[1]) + fphi * (field[7] - field[5])));
      dBdr[j] =
        sr *
        (gz * (gphi * (field[1] - field[0]) + fphi * (field[5] - field[4])) +
         fz * (gphi * (field[3] - field[2]) + fphi * (field[7] - field[6])));
      dBdphi[j] =
        sphi * (gz * (gr * (field[4] - field[0]) + fr * (field[5] - field[1])) +
                fz * (gr * (field[6] - field[2]) + fr * (field[7] - field[3])));
    }
 
    // convert to cartesian coordinates
    const double cc = c * c;
    const double cs = c * s;
    const double ss = s * s;
    const double ccinvr = cc * invr;
    const double csinvr = cs * invr;
    const double ssinvr = ss * invr;
    const double sinvr = s * invr;
    const double cinvr = c * invr;
    deriv[0] = cc * dBdr[1] - cs * dBdr[2] - csinvr * dBdphi[1] +
               ssinvr * dBdphi[2] + sinvr * B[1];
    deriv[1] = cs * dBdr[1] - ss * dBdr[2] + ccinvr * dBdphi[1] -
               csinvr * dBdphi[2] - cinvr * B[1];
    deriv[2] = c * dBdz[1] - s * dBdz[2];
    deriv[3] = cs * dBdr[1] + cc * dBdr[2] - ssinvr * dBdphi[1] -
               csinvr * dBdphi[2] - sinvr * B[0];
    deriv[4] = ss * dBdr[1] + cs * dBdr[2] + csinvr * dBdphi[1] +
               ccinvr * dBdphi[2] + cinvr * B[0];
    deriv[5] = s * dBdz[1] + c * dBdz[2];
    deriv[6] = c * dBdr[0] - sinvr * dBdphi[0];
    deriv[7] = s * dBdr[0] + cinvr * dBdphi[0];
    deriv[8] = dBdz[0];
  }
}

inside()

bool BFieldCache::inside	(	double	z,
		double	r,
		double	phi
	)		const

invalidate()

void BFieldCache::invalidate

(

)

setBscale()

void BFieldCache::setBscale

(

double

bscale

)

setField()

void BFieldCache::setField	(	const CxxUtils::vec< double, 8 > &	field1,
		const CxxUtils::vec< double, 8 > &	field2,
		const CxxUtils::vec< double, 8 > &	field3
	)

setRange()

void BFieldCache::setRange	(	double	zmin,
		double	zmax,
		double	rmin,
		double	rmax,
		double	phimin,
		double	phimax
	)

Member Data Documentation

m_field

double BFieldCache::m_field[3][8]

private

Definition at line 74 of file BFieldCache.h.

m_invphi

double BFieldCache::m_invphi

private

Definition at line 72 of file BFieldCache.h.

m_invr

double BFieldCache::m_invr

private

Definition at line 71 of file BFieldCache.h.

m_invz

double BFieldCache::m_invz

private

Definition at line 70 of file BFieldCache.h.

m_phimax

double BFieldCache::m_phimax = -1.0

private

Definition at line 68 of file BFieldCache.h.

m_phimin

double BFieldCache::m_phimin = 0.0

private

Definition at line 67 of file BFieldCache.h.

m_rmax

double BFieldCache::m_rmax = 0.0

private

Definition at line 65 of file BFieldCache.h.

m_rmin

double BFieldCache::m_rmin = 0.0

private

Definition at line 64 of file BFieldCache.h.

m_scale

double BFieldCache::m_scale

private

Definition at line 73 of file BFieldCache.h.

m_zmax

double BFieldCache::m_zmax = 0.0

private

Definition at line 62 of file BFieldCache.h.

m_zmin

double BFieldCache::m_zmin = 0.0

private

Definition at line 61 of file BFieldCache.h.

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The documentation for this class was generated from the following files:

• BFieldCache.h
• BFieldCache.cxx