138 lines
4.9 KiB
C++
138 lines
4.9 KiB
C++
/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkMinimalStandardRandomSequence.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 vtkMinimalStandardRandomSequence
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* @brief Park and Miller Sequence of pseudo random numbers
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*
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* vtkMinimalStandardRandomSequence is a sequence of statistically independent
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* pseudo random numbers uniformly distributed between 0.0 and 1.0.
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*
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* The sequence is generated by a prime modulus multiplicative linear
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* congruential generator (PMMLCG) or "Lehmer generator" with multiplier 16807
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* and prime modulus 2^(31)-1. The authors calls it
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* "minimal standard random number generator"
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*
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* ref: "Random Number Generators: Good Ones are Hard to Find,"
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* by Stephen K. Park and Keith W. Miller in Communications of the ACM,
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* 31, 10 (Oct. 1988) pp. 1192-1201.
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* Code is at page 1195, "Integer version 2"
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*
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* Correctness test is described in first column, page 1195:
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* A seed of 1 at step 1 should give a seed of 1043618065 at step 10001.
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*/
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#ifndef vtkMinimalStandardRandomSequence_h
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#define vtkMinimalStandardRandomSequence_h
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#include "vtkCommonCoreModule.h" // For export macro
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#include "vtkRandomSequence.h"
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class VTKCOMMONCORE_EXPORT vtkMinimalStandardRandomSequence : public vtkRandomSequence
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{
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public:
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///@{
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/**
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* Standard methods for instantiation, type information, and printing.
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*/
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static vtkMinimalStandardRandomSequence* New();
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vtkTypeMacro(vtkMinimalStandardRandomSequence, vtkRandomSequence);
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void PrintSelf(ostream& os, vtkIndent indent) override;
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///@}
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/**
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* Satisfy general API of vtkRandomSequence superclass. Initialize the
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* sequence with a seed.
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*/
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void Initialize(vtkTypeUInt32 seed) override { this->SetSeed(seed); }
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/**
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* Set the seed of the random sequence.
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* The following pre-condition is stated page 1197, second column:
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* valid_seed: value>=1 && value<=2147483646
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* 2147483646=(2^31)-2
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* This method does not have this criterium as a pre-condition (ie it will
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* not fail if an incorrect seed value is passed) but the value is silently
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* changed to fit in the valid range [1,2147483646].
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* 2147483646 is added to a null or negative value.
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* 2147483647 is changed to be 1 (ie 2147483646 is subtracted).
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* Implementation note: it also performs 3 calls to Next() to avoid the
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* bad property that the first random number is proportional to the seed
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* value.
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*/
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void SetSeed(int value);
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/**
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* Set the seed of the random sequence. There is no extra internal
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* adjustment. Only useful for writing correctness test.
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* The following pre-condition is stated page 1197, second column
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* 2147483646=(2^31)-2
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* This method does not have this criterium as a pre-condition (ie it will
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* not fail if an incorrect seed value is passed) but the value is silently
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* changed to fit in the valid range [1,2147483646].
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* 2147483646 is added to a null or negative value.
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* 2147483647 is changed to be 1 (ie 2147483646 is subtracted).
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*/
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void SetSeedOnly(int value);
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/**
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* Get the seed of the random sequence.
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* Only useful for writing correctness test.
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*/
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int GetSeed();
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/**
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* Current value
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* \post unit_range: result>=0.0 && result<=1.0
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*/
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double GetValue() override;
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/**
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* Move to the next number in the random sequence.
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*/
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void Next() override;
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/**
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* Convenient method to return a value in a specific range from the
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* range [0,1. There is an initial implementation that can be overridden
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* by a subclass.
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* There is no pre-condition on the range:
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* - it can be in increasing order: rangeMin<rangeMax
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* - it can be empty: rangeMin=rangeMax
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* - it can be in decreasing order: rangeMin>rangeMax
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* \post result_in_range:
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* (rangeMin<=rangeMax && result>=rangeMin && result<=rangeMax)
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* || (rangeMax<=rangeMin && result>=rangeMax && result<=rangeMin)
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*/
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virtual double GetRangeValue(double rangeMin, double rangeMax);
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/**
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* Get the next value in the sequence within a range.
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*
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* \see vtkMinimalStandardRandomSequence::GetRangeValue
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*/
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double GetNextRangeValue(double rangeMin, double rangeMax);
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protected:
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vtkMinimalStandardRandomSequence();
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~vtkMinimalStandardRandomSequence() override;
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int Seed;
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private:
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vtkMinimalStandardRandomSequence(const vtkMinimalStandardRandomSequence&) = delete;
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void operator=(const vtkMinimalStandardRandomSequence&) = delete;
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};
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#endif // #ifndef vtkMinimalStandardRandomSequence_h
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