Belle2::TOP::func Namespace Reference

commonly used functions More...

Functions
long	lround (double x)
	Rounds to the nearest integer, halfway cases away from zero.
double	unfold (double x, int nx, double A)
	unfold a coordinate.
double	unfold (double kx, int nx)
	unfold a direction.
void	fold (double xu, double A, double &x, double &kx, int &nx)
	fold a coordinate (inverse of unfold).
double	clip (double x, int Nx, double A, double xmi, double xma)
	Performs a clip on x w.r.t xmi and xma.
int	getNumOfEven (int j1, int j2)
	Returns number of even numbers in the range given by arguments.
double	within2PI (double angle)
	Returns angle within 0 and 2PI.
void	rotateUz (ROOT::Math::XYZVector &vec, const ROOT::Math::XYZVector &z_Axis)
	Replacement for a function TVector3::RotateUz which is not implemented in GenVector classes.

Detailed Description

commonly used functions

Function Documentation

clip()

double clip ( double x, int Nx, double A, double xmi, double xma )

inline

Performs a clip on x w.r.t xmi and xma.

Parameters

x	true coordinate
Nx	signed number of reflections
A	size for folding/unfolding
xmi	lower limit on unfolded coordinate x
xma	upper limit on unfolded coordinate x

Returns

clipped x

Definition at line 98 of file func.h.

      {
        x = unfold(x, Nx, A);
        x = std::max(std::min(x, xma), xmi) - Nx * A;
        if (Nx % 2 != 0) x = -x;
        return x;
      }

fold()

void fold ( double xu, double A, double & x, double & kx, int & nx )

inline

fold a coordinate (inverse of unfold).

Parameters

xu	unfolded coordinate (position of image)
A	size for folding
x	true position [out]
kx	true direction component [in/out]
nx	signed number of reflections [out]

Definition at line 79 of file func.h.

      {
        nx = func::lround(xu / A);
        x = xu - nx * A;
        if (nx % 2 != 0) {
          x = -x;
          kx = -kx;
        }
      }

getNumOfEven()

int getNumOfEven ( int j1, int j2 )

inline

Returns number of even numbers in the range given by arguments.

Parameters

j1	first number
j2	last number (exclusive)

Returns

number of even numbers

Definition at line 112 of file func.h.

      {
        return (j2 - j1 + 1 - std::abs(j1) % 2) / 2;
      }

lround()

long lround ( double x )

inline

Rounds to the nearest integer, halfway cases away from zero.

Bit-for-bit equivalent to std::lround, but inlined instead of calling into libm, which matters because this is used in the innermost ray-tracing loops.

Parameters

x	value to round

Returns

the rounded value

Definition at line 31 of file func.h.

      {
        // 2^52: above it every double is already an integer, and the conversion below could overflow
        if (std::abs(x) < 4503599627370496.0) {
          x += 0.5;
          long n = static_cast<long>(std::abs(x)); // truncation towards zero
          if (x > 0) return n;
          return -(n + 1);
        }
        return std::lround(x); // also takes care of NaN and infinity
      }

rotateUz()

void rotateUz ( ROOT::Math::XYZVector & vec, const ROOT::Math::XYZVector & z_Axis )

inline

Replacement for a function TVector3::RotateUz which is not implemented in GenVector classes.

Parameters

vec	vector to be rotated from frame S' [in] to frame S [out]
z_Axis	vector representing z-axis of the frame S' expressed in the coordinates of frame S

Definition at line 134 of file func.h.

      {
        auto zAxis = z_Axis.Unit();
        double cth = zAxis.Z();
        double sth = sqrt(1 - cth * cth);
        if (sth == 0) {
          if (cth < 0) vec = -vec;
          return;
        }
        double cfi = zAxis.X() / sth;
        double sfi = zAxis.Y() / sth;
        // rotation by theta around y then by phi around z
        double x = cth * vec.X() + sth * vec.Z();
        double y = vec.Y();
        double z = -sth * vec.X() + cth * vec.Z();
        vec.SetX(cfi * x - sfi * y);
        vec.SetY(sfi * x + cfi * y);
        vec.SetZ(z);
      }

unfold() [1/2]

double unfold ( double kx, int nx )

inline

unfold a direction.

Parameters

kx	true direction component
nx	signed number of reflections

Returns

unfolded direction component

Definition at line 64 of file func.h.

      {
        if (nx % 2 == 0) return kx;
        else return -kx;
      }

unfold() [2/2]

double unfold ( double x, int nx, double A )

inline

unfold a coordinate.

Parameters

x	true position
nx	signed number of reflections
A	size for unfolding

Returns

unfolded coordinate (position of image)

Definition at line 51 of file func.h.

      {
        if (nx % 2 == 0) return (nx * A + x);
        else return (nx * A - x);
      }

within2PI()

double within2PI ( double angle )

inline

Returns angle within 0 and 2PI.

Parameters

angle

angle

Returns

angle within 0 and 2PI

Definition at line 122 of file func.h.

      {
        angle = fmod(angle, 2 * M_PI);
        if (angle < 0) angle += 2 * M_PI;
        return angle;
      }