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/*=========================================================================
Program: Visualization Toolkit
Module: vtkMinimalStandardRandomSequence.cxx
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.
=========================================================================*/
#include "vtkMinimalStandardRandomSequence.h"
#include "vtkObjectFactory.h"
#include <cassert>
VTK_ABI_NAMESPACE_BEGIN
vtkStandardNewMacro(vtkMinimalStandardRandomSequence);
const int VTK_K_A = 16807;
const int VTK_K_M = 2147483647; // Mersenne prime 2^(31)-1
const int VTK_K_Q = 127773; // M/A
const int VTK_K_R = 2836; // M%A
//------------------------------------------------------------------------------
vtkMinimalStandardRandomSequence::vtkMinimalStandardRandomSequence()
{
this->Seed = 1;
}
//------------------------------------------------------------------------------
vtkMinimalStandardRandomSequence::~vtkMinimalStandardRandomSequence() = default;
//------------------------------------------------------------------------------
void vtkMinimalStandardRandomSequence::SetSeedOnly(int value)
{
this->Seed = value;
// fit the seed to the valid range [1,2147483646]
if (this->Seed < 1)
{
this->Seed += 2147483646;
}
else
{
if (this->Seed == 2147483647)
{
this->Seed = 1;
}
}
}
//------------------------------------------------------------------------------
void vtkMinimalStandardRandomSequence::SetSeed(int value)
{
this->SetSeedOnly(value);
// the first random number after setting the seed is proportional to the
// seed value. To help solve this, call Next() a few times.
// This doesn't ruin the repeatability of Next().
this->Next();
this->Next();
this->Next();
}
//------------------------------------------------------------------------------
int vtkMinimalStandardRandomSequence::GetSeed()
{
return this->Seed;
}
//------------------------------------------------------------------------------
double vtkMinimalStandardRandomSequence::GetValue()
{
double result = static_cast<double>(this->Seed) / VTK_K_M;
assert("post: unit_range" && result >= 0.0 && result <= 1.0);
return result;
}
//------------------------------------------------------------------------------
void vtkMinimalStandardRandomSequence::Next()
{
int hi = this->Seed / VTK_K_Q;
int lo = this->Seed % VTK_K_Q;
this->Seed = VTK_K_A * lo - VTK_K_R * hi;
if (this->Seed <= 0)
{
this->Seed += VTK_K_M;
}
}
//------------------------------------------------------------------------------
double vtkMinimalStandardRandomSequence::GetRangeValue(double rangeMin, double rangeMax)
{
double result;
if (rangeMin == rangeMax)
{
result = rangeMin;
}
else
{
result = rangeMin + this->GetValue() * (rangeMax - rangeMin);
}
assert("post: valid_result" &&
((rangeMin <= rangeMax && result >= rangeMin && result <= rangeMax) ||
(rangeMax <= rangeMin && result >= rangeMax && result <= rangeMin)));
return result;
}
//------------------------------------------------------------------------------
double vtkMinimalStandardRandomSequence::GetNextRangeValue(double rangeMin, double rangeMax)
{
this->Next();
return this->GetRangeValue(rangeMin, rangeMax);
}
//------------------------------------------------------------------------------
void vtkMinimalStandardRandomSequence::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os, indent);
}
VTK_ABI_NAMESPACE_END
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