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// miscfp.cc -- misc floating-point functions
//
// hypot3 - 3D Euclidean distance
// arctan_xy - 4-quadrant arc tangent
//
#include <math.h>
#include "util++.hh"
//******************************************************************************
//
// This function computes the 3-dimensional Euclidean distance,
// analogously to the standard math library function hypot(2) .
//
// Arguments:
// (x,y,z) = (in) The rectangular coordinates of a point in $\Re^3$.
//
// Result:
// The function returns the Euclidean distance of (x,y,z) from the origin.
//
// Bugs:
// Unlike hypot(2), this function takes no special care to avoid
// unwarranted IEEE exceptions if any of |x|, |y|, or |z| is close to
// the overflow and/or underflow threshold.
//
namespace jtutil
{
double hypot3(double x, double y, double z)
{
return std::sqrt(x*x + y*y + z*z);
}
};
//******************************************************************************
//
// This function computes a four-quadrant arctangent, using what I think
// is the "right" ordering of the arguments, and returning 0.0 if both
// arguments are 0.0.
//
// Arguments:
// (x,y) = (in) The rectangular coordinates of a point in $\Re^2$.
//
// Result:
// The function returns a value $\theta$ such that $x + iy = R e^{i\theta}$ for
// some real $R$, i.e. it returns the angle between the positive $x$ axis and
// the line joining the origin and the point $(x,y)$.
//
namespace jtutil
{
double arctan_xy(double x, double y)
{
return ((x == 0.0) && (y == 0.0))
?
: std::atan2(y, x); // note reversed argument order (y,x)!!
}
};
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