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101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
3 weeks ago
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/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkMathUtilities.h
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notice for more information.
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=========================================================================*/
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/**
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* @class vtkMathUtilities
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* @brief templated utility math functions intended for
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* internal use in tests etc.
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*
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*
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* Provide a set of inline, lightweight templated math utility functions.
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* The initial motivation is to provide a few lightweight functions to help in
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* testing and internal implementation files.
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*/
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#ifndef vtkMathUtilities_h
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#define vtkMathUtilities_h
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#include <cmath>
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#include <limits>
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namespace vtkMathUtilities
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{
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/**
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* Perform a fuzzy compare of floats/doubles.
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*/
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template <class A>
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bool FuzzyCompare(A a, A b)
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{
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return fabs(a - b) < std::numeric_limits<A>::epsilon();
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}
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/**
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* Perform a fuzzy compare of floats/doubles, specify the allowed tolerance
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*/
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template <class A>
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bool FuzzyCompare(A a, A b, A epsilon)
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{
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return fabs(a - b) < epsilon;
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}
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/**
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* Performs safe division that catches overflow and underflow.
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*/
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template <class A>
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A SafeDivision(A a, A b)
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{
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// Avoid overflow
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if ((b < static_cast<A>(1)) && (a > b * std::numeric_limits<A>::max()))
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{
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return std::numeric_limits<A>::max();
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}
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// Avoid underflow
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if ((a == static_cast<A>(0)) ||
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((b > static_cast<A>(1)) && (a < b * std::numeric_limits<A>::min())))
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{
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return static_cast<A>(0);
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}
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// safe to do the division
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return (a / b);
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}
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//@{
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/**
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* A slightly different fuzzy comparator that checks if two values are
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* "nearly" equal based on Knuth, "The Art of Computer Programming (vol II)"
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*/
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template <class A>
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bool NearlyEqual(A a, A b, A tol = std::numeric_limits<A>::epsilon())
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{
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A absdiff = fabs(a - b);
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A d1 = vtkMathUtilities::SafeDivision<A>(absdiff, fabs(a));
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A d2 = vtkMathUtilities::SafeDivision<A>(absdiff, fabs(b));
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//@}
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if ((d1 <= tol) || (d2 <= tol))
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{
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return true;
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}
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return false;
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}
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} // End vtkMathUtilities namespace.
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#endif // vtkMathUtilities_h
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// VTK-HeaderTest-Exclude: vtkMathUtilities.h
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