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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 <cassert>
#include "vtkObjectFactory.h"
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()
{
}
// ----------------------------------------------------------------------------
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(void)
{
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;
}
// ----------------------------------------------------------------------------
void vtkMinimalStandardRandomSequence::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os, indent);
}
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