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vtkMathUtilities.h
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1/*=========================================================================
2
3 Program: Visualization Toolkit
4 Module: vtkMathUtilities.h
5
6 Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
7 All rights reserved.
8 See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
9
10 This software is distributed WITHOUT ANY WARRANTY; without even
11 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
12 PURPOSE. See the above copyright notice for more information.
13
14=========================================================================*/
15
30#ifndef vtkMathUtilities_h
31#define vtkMathUtilities_h
32
33#include <cmath>
34#include <limits>
35
37{
38
42template<class A>
43bool FuzzyCompare(A a, A b)
44{
45 return fabs(a - b) < std::numeric_limits<A>::epsilon();
46}
47
51template<class A>
52bool FuzzyCompare(A a, A b, A epsilon)
53{
54 return fabs(a - b) < epsilon;
55}
56
60template<class A>
61A SafeDivision(A a, A b)
62{
63 // Avoid overflow
64 if( (b < static_cast<A>(1)) && (a > b*std::numeric_limits<A>::max()) )
65 {
67 }
68
69 // Avoid underflow
70 if( (a == static_cast<A>(0)) ||
71 ((b > static_cast<A>(1)) && (a < b*std::numeric_limits<A>::min())) )
72 {
73 return static_cast<A>(0);
74 }
75
76 // safe to do the division
77 return( a/b );
78}
79
81
85template<class A>
86bool NearlyEqual(A a, A b, A tol=std::numeric_limits<A>::epsilon())
87{
88 A absdiff = fabs(a-b);
89 A d1 = vtkMathUtilities::SafeDivision<A>(absdiff,fabs(a));
90 A d2 = vtkMathUtilities::SafeDivision<A>(absdiff,fabs(b));
92
93 if( (d1 <= tol) || (d2 <= tol) )
94 {
95 return true;
96 }
97 return false;
98}
99
100} // End vtkMathUtilities namespace.
101
102#endif // vtkMathUtilities_h
103// VTK-HeaderTest-Exclude: vtkMathUtilities.h
bool FuzzyCompare(A a, A b)
Perform a fuzzy compare of floats/doubles.
bool NearlyEqual(A a, A b, A tol=std::numeric_limits< A >::epsilon())
A slightly different fuzzy comparator that checks if two values are "nearly" equal based on Knuth,...
A SafeDivision(A a, A b)
Performs safe division that catches overflow and underflow.
#define max(a, b)