You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
101 lines
2.4 KiB
C++
101 lines
2.4 KiB
C++
/*=========================================================================
|
|
|
|
Program: Visualization Toolkit
|
|
Module: vtkMathUtilities.h
|
|
|
|
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
|
|
All rights reserved.
|
|
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
|
|
|
|
This software is distributed WITHOUT ANY WARRANTY; without even
|
|
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
|
|
PURPOSE. See the above copyright notice for more information.
|
|
|
|
=========================================================================*/
|
|
|
|
/**
|
|
* @class vtkMathUtilities
|
|
* @brief templated utility math functions intended for
|
|
* internal use in tests etc.
|
|
*
|
|
*
|
|
* Provide a set of inline, lightweight templated math utility functions.
|
|
* The initial motivation is to provide a few lightweight functions to help in
|
|
* testing and internal implementation files.
|
|
*/
|
|
|
|
#ifndef vtkMathUtilities_h
|
|
#define vtkMathUtilities_h
|
|
|
|
#include <cmath>
|
|
#include <limits>
|
|
|
|
namespace vtkMathUtilities
|
|
{
|
|
|
|
/**
|
|
* Perform a fuzzy compare of floats/doubles.
|
|
*/
|
|
template<class A>
|
|
bool FuzzyCompare(A a, A b)
|
|
{
|
|
return fabs(a - b) < std::numeric_limits<A>::epsilon();
|
|
}
|
|
|
|
/**
|
|
* Perform a fuzzy compare of floats/doubles, specify the allowed tolerance
|
|
*/
|
|
template<class A>
|
|
bool FuzzyCompare(A a, A b, A epsilon)
|
|
{
|
|
return fabs(a - b) < epsilon;
|
|
}
|
|
|
|
/**
|
|
* Performs safe division that catches overflow and underflow.
|
|
*/
|
|
template<class A>
|
|
A SafeDivision(A a, A b)
|
|
{
|
|
// Avoid overflow
|
|
if( (b < static_cast<A>(1)) && (a > b*std::numeric_limits<A>::max()) )
|
|
{
|
|
return std::numeric_limits<A>::max();
|
|
}
|
|
|
|
// Avoid underflow
|
|
if( (a == static_cast<A>(0)) ||
|
|
((b > static_cast<A>(1)) && (a < b*std::numeric_limits<A>::min())) )
|
|
{
|
|
return static_cast<A>(0);
|
|
}
|
|
|
|
// safe to do the division
|
|
return( a/b );
|
|
}
|
|
|
|
//@{
|
|
/**
|
|
* A slightly different fuzzy comparator that checks if two values are
|
|
* "nearly" equal based on Knuth, "The Art of Computer Programming (vol II)"
|
|
*/
|
|
template<class A>
|
|
bool NearlyEqual(A a, A b, A tol=std::numeric_limits<A>::epsilon())
|
|
{
|
|
A absdiff = fabs(a-b);
|
|
A d1 = vtkMathUtilities::SafeDivision<A>(absdiff,fabs(a));
|
|
A d2 = vtkMathUtilities::SafeDivision<A>(absdiff,fabs(b));
|
|
//@}
|
|
|
|
if( (d1 <= tol) || (d2 <= tol) )
|
|
{
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
} // End vtkMathUtilities namespace.
|
|
|
|
#endif // vtkMathUtilities_h
|
|
// VTK-HeaderTest-Exclude: vtkMathUtilities.h
|