tnt_math_utils.h.svn-base

来自「fast marching method」· SVN-BASE 代码 · 共 66 行

#ifndef MATH_UTILS_H
#define MATH_UTILS_H

#include <math.h>
/* needed for sqrt() below */

namespace TNT
{
/**
	@returns hypotenuse of real (non-complex) scalars a and b by 
	avoiding underflow/overflow
	using (a * sqrt( 1 + (b/a) * (b/a))), rather than
	sqrt(a*a + b*b).
*/
template <class Real>
Real hypot(const Real &a, const Real &b)
{
	
	if (a== 0)
		return abs(b);
	else
	{
		Real c = b/a;
		return a * sqrt(1 + c*c);
	}
}

/**
	@returns the minimum of scalars a and b.
*/
#undef min
template <class Scalar>
Scalar min(const Scalar &a, const Scalar &b)
{
	return  a < b ? a : b;
}

/**
	@returns the maximum of scalars a and b.
*/
#undef max
template <class Scalar>
Scalar max(const Scalar &a, const Scalar &b)
{
	return  a > b ? a : b;
}

/* added by G.Peyre */
#define		TNT_MIN(a, b)       ((a) < (b) ? (a) : (b))			//!<	Returns the min value between a and b
#define		TNT_MAX(a, b)       ((a) > (b) ? (a) : (b))			//!<	Returns the max value between a and b
#define		TNT_ABS(a)       ((a) > 0 ? (a) : -(a))			//!<	Returns the absolute value a


/**
	@returns the absolute value of a real (no-complex) scalar.
*/
template <class Real>
Real abs(const Real &a)
{
	return  (a > 0 ? a : -a);
}

}
#endif
/* MATH_UTILS_H */