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EASTL/test/packages/EAStdC/test/source/TestRandom.cpp
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2024-07-02 18:10:39 +02:00

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///////////////////////////////////////////////////////////////////////////////
// Copyright (c) Electronic Arts Inc. All rights reserved.
///////////////////////////////////////////////////////////////////////////////
#ifdef _MSC_VER
#pragma warning(disable: 4244) // This warning is being generated due to a bug in VC++.
#endif
#include <EABase/eabase.h>
#include <EAStdC/EARandom.h>
#include <EAStdC/EARandomDistribution.h>
#include <EAStdCTest/EAStdCTest.h>
#include <EATest/EATest.h>
#include <EASTL/bitset.h>
#ifdef _MSC_VER
#pragma warning(push, 0)
#pragma warning(disable: 4275) // non dll-interface class 'stdext::exception' used as base for dll-interface class 'std::bad_cast'
#endif
#ifndef EA_PLATFORM_ANDROID
#include <algorithm>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#if defined(_MSC_VER) && defined(EA_PLATFORM_MICROSOFT)
#include <crtdbg.h>
#endif
#if defined(EA_PLATFORM_WINDOWS)
#include <Windows.h>
#endif
#if EASTDC_TIME_H_AVAILABLE
#include <time.h>
#endif
#ifdef _MSC_VER
#pragma warning(pop)
#pragma warning(push)
#pragma warning(disable: 4365) // 'argument' : conversion from 'int' to 'uint32_t', signed/unsigned mismatch
#endif
using namespace EA::StdC;
// Forward declarations
void rt_init(int binmode);
void rt_add(void* buf, int bufl);
void rt_end(double* r_ent, double* r_chisq, double* r_mean, double* r_montepicalc, double* r_scc);
static int TestDieHard()
{
int nErrorCount(0);
// Write out 9MB file for DieHard tests.
#if defined(EA_PLATFORM_WINDOWS) && EA_WINAPI_FAMILY_PARTITION(EA_WINAPI_PARTITION_DESKTOP)
if(GetAsyncKeyState(VK_SCROLL)) // If the Scroll Lock key is alive.
{
// Ideally we would port the DieHard code to here, but it is not well
// written for modularity. For the time being, we write out the 9MB
// data file that DieHard.exe can analyze. As of this writing, DieHard.exe
// is part of the EAOS UTF Research repository.
{
RandomLinearCongruential randomLC;
FILE* pFile = fopen("RandomLinearCongruentialData.txt", "w");
if(pFile)
{
for(uint32_t i = 0; i < 12000000; i += 4)
{
const uint32_t value = randomLC.RandomUint32Uniform();
fwrite(&value, 1, 4, pFile);
}
fclose(pFile);
}
}
{
RandomMersenneTwister randomMT;
FILE* pFile = fopen("RandomMersenneTwisterData.txt", "w");
if(pFile)
{
for(uint32_t i = 0; i < 12000000; i += 4)
{
const uint32_t value = randomMT.RandomUint32Uniform();
fwrite(&value, 1, 4, pFile);
}
fclose(pFile);
}
}
}
#endif
return nErrorCount;
}
namespace
{
#if defined(EA_PLATFORM_DESKTOP) && !defined(EA_DEBUG)
// This exists for the purpose of testing distributions. It implements a seed that is continuously
// increasting and thus over the course of 0x100000000 (2^32) calls to RandomUint32Uniform returns a statistically
// even distribution of bits. Note that truly random data won't behave this way and formal tests for
// randomness would identify this as being not random. But that's not the purpose of this class;
// the purpose is to help test if there are distribution problems in the range and distribution adapters.
// Note that it's important that you do 0x100000000 calls with this or else the results of it won't
// be evenly distributed as designed.
class FakeIncrementingRandom
{
public:
FakeIncrementingRandom()
: mnSeed(0) {}
//FakeIncrementingRandom(const FakeIncrementingRandom& x)
// : mnSeed(x.mnSeed) {}
//FakeIncrementingRandom& operator=(const FakeIncrementingRandom& x)
// { mnSeed = x.mnSeed; return *this; }
//uint32_t GetSeed() const
// { return mnSeed; }
//void SetSeed(uint32_t nSeed)
// { mnSeed = nSeed; }
//uint32_t operator()(uint32_t nLimit)
// { return EA::StdC::RandomLimit(*this, nLimit); }
uint32_t RandomUint32Uniform()
{ return mnSeed++; }
protected:
uint32_t mnSeed;
};
#endif
}
// TestRandom
// Note that thus function itself is not meant as a comprehensive
// test for randomness. Instead this function does a basic test
// for randomness and then optionally writes out files to disk
// for analysis by a comprehensive tool like DieHard.
//
int TestRandom()
{
int nErrorCount(0);
{ // Bug report regression.
// User Fei Jiang reports that RandomLinearCongruential::RandomUnit32Uniform(uint32_t nLimit) returns
// different values on PS3 in debug vs. debug-opt builds with SN compiler.
RandomLinearCongruential rlc(UINT32_C(2474210934));
uint32_t seed = rlc.GetSeed();
//EA::UnitTest::Report("seed: %u\n", (unsigned)seed);
EATEST_VERIFY(seed == UINT32_C(2474210934));
uint32_t result = rlc.RandomUint32Uniform(57);
//EA::UnitTest::Report("result: %u\n", (unsigned)result);
EATEST_VERIFY(result == 23); // 743483
}
// Load priming
// We call a function from each generator used below to minimize
// an loading effects on benchmarking.
int rTemp = rand();
EATEST_VERIFY(rTemp >= 0); // "Returns a pseudo-random integral number in the range 0 to RAND_MAX."
RandomLinearCongruential randomLCPrimer;
randomLCPrimer.RandomUint32Uniform();
RandomMersenneTwister randomMTPrimer;
randomMTPrimer.RandomUint32Uniform();
TestDieHard();
//#define SPEED_TESTS_ENABLED
#ifdef SPEED_TESTS_ENABLED
// Speed tests.
// Results on a Pentium 4 PC were:
// rand(): 8172 clocks.
// RandomLinearCongruential: 4687 clocks.
// RandomMersenneTwister: 6157 clocks.
{
clock_t timeStart;
clock_t timeTotal;
const int kIterationCount(5000000);
timeStart = clock();
for(int i(0); i < kIterationCount; i++)
EA::UnitTest::WriteToEnsureFunctionCalled() = (int)rand();
timeTotal = clock() - timeStart;
EA::UnitTest::Report("rand(): %d clocks.\n", (int)timeTotal);
timeStart = clock();
for(int i(0); i < kIterationCount; i++)
EA::UnitTest::WriteToEnsureFunctionCalled() = (int)(rand() % 37997);
timeTotal = clock() - timeStart;
EA::UnitTest::Report("rand() w/limit: %d clocks.\n", (int)timeTotal);
RandomLinearCongruential randomLC;
timeStart = clock();
for(int i(0); i < kIterationCount; i++)
EA::UnitTest::WriteToEnsureFunctionCalled() = (int)randomLC.RandomUint32Uniform();
timeTotal = clock() - timeStart;
EA::UnitTest::Report("RandomLinearCongruential: %d clocks.\n", (int)timeTotal);
timeStart = clock();
for(int i(0); i < kIterationCount; i++)
EA::UnitTest::WriteToEnsureFunctionCalled() = (int)randomLC.RandomUint32Uniform(37997);
timeTotal = clock() - timeStart;
EA::UnitTest::Report("RandomLinearCongruential w/limit: %d clocks.\n", (int)timeTotal);
RandomMersenneTwister randomMT;
timeStart = clock();
for(int i(0); i < kIterationCount; i++)
EA::UnitTest::WriteToEnsureFunctionCalled() = (int)randomMT.RandomUint32Uniform();
timeTotal = clock() - timeStart;
EA::UnitTest::Report("RandomMersenneTwister: %d clocks.\n", (int)timeTotal);
timeStart = clock();
for(int i(0); i < kIterationCount; i++)
EA::UnitTest::WriteToEnsureFunctionCalled() = (int)randomMT.RandomUint32Uniform(32997);
timeTotal = clock() - timeStart;
EA::UnitTest::Report("RandomMersenneTwister w/limit: %d clocks.\n", (int)timeTotal);
}
#endif
// Test output ranges
{ // RandomLinearCongruential test
RandomLinearCongruential random;
int32_t nRandom;
double dRandom;
for(unsigned i(0); i < 100; i++)
{
for(uint32_t j(5); j < (UINT32_MAX / 2); j *= 5)
{
uint32_t nU32 = random.RandomUint32Uniform(j);
EATEST_VERIFY(nU32 < j);
dRandom = random.RandomDoubleUniform((double)j);
EATEST_VERIFY(0.0 <= dRandom && dRandom < j);
dRandom = random.RandomDoubleUniform();
EATEST_VERIFY(0.0 <= dRandom && dRandom < 1.0);
}
nRandom = Random2(random);
EATEST_VERIFY(nRandom < 2);
nRandom = Random4(random);
EATEST_VERIFY(nRandom < 4);
nRandom = Random8(random);
EATEST_VERIFY(nRandom < 8);
nRandom = Random16(random);
EATEST_VERIFY(nRandom < 16);
nRandom = Random32(random);
EATEST_VERIFY(nRandom < 32);
nRandom = Random64(random);
EATEST_VERIFY(nRandom < 642);
nRandom = Random128(random);
EATEST_VERIFY(nRandom < 128);
nRandom = Random256(random);
EATEST_VERIFY(nRandom < 256);
// RandomPowerOfTwo
for(uint32_t k(1); k < 31; k++)
{
nRandom = RandomPowerOfTwo(random, k);
EATEST_VERIFY((uint32_t)nRandom < (uint32_t)(2 << k));
}
// RandomInt32UniformRange
for(int32_t nBegin(-10000); nBegin < 10000; nBegin += Random256(random))
{
int32_t nEnd = nBegin + 1 + Random256(random);
int32_t iRandom = RandomInt32UniformRange(random, nBegin, nEnd);
EATEST_VERIFY_F((iRandom >= nBegin) && (iRandom < nEnd), "RandomInt32UniformRange failure: iRandom: %I32d, nBegin: %I32d, nEnd: %I32d", iRandom, nBegin, nEnd);
}
// RandomDoubleUniformRange
for(int32_t dBegin(-10000); dBegin < 10000; dBegin += Random256(random))
{
int32_t dEnd = dBegin + 1 + Random256(random);
dRandom = RandomDoubleUniformRange(random, (double)dBegin, (double)dEnd);
EATEST_VERIFY_F((dRandom >= dBegin) && (dRandom < dEnd), "RandomDoubleUniformRange failure: dRandom: %f, dBegin: %f, dEnd: %f", dRandom, (double)dBegin, (double)dEnd);
}
// RandomUint32WeightedChoice
const uint32_t kLimit = 37;
float weights[kLimit];
for(uint32_t q(0); q < kLimit; q++)
weights[q] = (float)RandomDoubleUniformRange(random, 0.5, 30.0);
for(uint32_t r(0); r < 1000; r++)
{
uint32_t nU32 = RandomUint32WeightedChoice(random, kLimit, weights);
EATEST_VERIFY_F(nU32 < kLimit, "RandomUint32WeightedChoice failure: nU32: %I32u, kLimit: %I32u", nU32, kLimit);
}
// RandomInt32GaussianRange
for(int r(0); r < 1000; r++)
{
const int32_t nBegin = (int32_t)random.RandomUint32Uniform(1000);
const int32_t nEnd = nBegin + (int32_t)random.RandomUint32Uniform(1000) + 1;
const int32_t iRandom = RandomInt32GaussianRange(random, nBegin, nEnd);
EATEST_VERIFY((iRandom >= nBegin) && (iRandom < nEnd));
}
// RandomFloatGaussianRange
for(int r(0); r < 1000; r++)
{
const float fBegin = (float)random.RandomDoubleUniform(1000);
const float fEnd = fBegin + (float)random.RandomDoubleUniform(1000) + 1.0f;
const float fRandom = RandomFloatGaussianRange(random, fBegin, fEnd);
EATEST_VERIFY((fRandom >= fBegin) && (fRandom < fEnd));
}
// RandomInt32TriangleRange
for(int r(0); r < 1000; r++)
{
const int32_t nBegin = (int32_t)random.RandomUint32Uniform(1000);
const int32_t nEnd = nBegin + (int32_t)random.RandomUint32Uniform(1000) + 1;
const int32_t iRandom = RandomInt32TriangleRange(random, nBegin, nEnd);
EATEST_VERIFY((iRandom >= nBegin) && (iRandom < nEnd));
}
// RandomFloatTriangleRange
for(int r(0); r < 1000; r++)
{
const float fBegin = (float)random.RandomDoubleUniform(1000);
const float fEnd = fBegin + (float)random.RandomDoubleUniform(1000) + 1.0f;
const float fRandom = RandomFloatTriangleRange(random, fBegin, fEnd);
EATEST_VERIFY((fRandom >= fBegin) && (fRandom < fEnd));
}
}
}
{ // RandomInt32Poisson
const float fMean = 5.f;
const size_t maxK = 30;
RandomMersenneTwister random;
for(int i = 0; i < 1000; i++)
{
int32_t rn = RandomInt32Poisson(random.RandomDoubleUniform(), fMean);
EATEST_VERIFY(rn < maxK);
}
}
{ // RandomLinearCongruential test
RandomMersenneTwister random;
int32_t nRandom;
double dRandom;
for(unsigned i(0); i < 1000; i++)
{
for(uint32_t j(5); j < UINT32_MAX / 2; j *= 5)
{
uint32_t nU32 = random.RandomUint32Uniform(j);
EATEST_VERIFY(nU32 < j);
dRandom = random.RandomDoubleUniform((double)j);
EATEST_VERIFY(0.0 <= dRandom && dRandom < j);
dRandom = random.RandomDoubleUniform();
EATEST_VERIFY(0.0 <= dRandom && dRandom < 1.0);
}
nRandom = Random2(random);
EATEST_VERIFY(nRandom < 2);
nRandom = Random4(random);
EATEST_VERIFY(nRandom < 4);
nRandom = Random8(random);
EATEST_VERIFY(nRandom < 8);
nRandom = Random16(random);
EATEST_VERIFY(nRandom < 16);
nRandom = Random32(random);
EATEST_VERIFY(nRandom < 32);
nRandom = Random64(random);
EATEST_VERIFY(nRandom < 64);
nRandom = Random128(random);
EATEST_VERIFY(nRandom < 128);
nRandom = Random256(random);
EATEST_VERIFY(nRandom < 256);
for(uint32_t k(1); k < 31; k++)
{
nRandom = RandomPowerOfTwo(random, k);
EATEST_VERIFY((uint32_t)nRandom < (uint32_t)(2 << k));
}
for(int nBegin(-10000); nBegin < 10000; nBegin += Random256(random))
{
int32_t nEnd = nBegin + 1 + Random256(random);
int32_t iRandom = RandomInt32UniformRange(random, nBegin, nEnd);
EATEST_VERIFY((iRandom >= nBegin) && (iRandom < nEnd));
}
for(int dBegin(-10000); dBegin < 10000; dBegin += Random256(random))
{
int32_t dEnd = dBegin + 1 + Random256(random);
dRandom = RandomDoubleUniformRange(random, (double)dBegin, (double)dEnd);
EATEST_VERIFY((dRandom >= dBegin) && (dRandom < dEnd));
}
const unsigned int kLimit = 37;
float weights[kLimit];
for(unsigned int q(0); q < kLimit; q++)
weights[q] = (float)RandomDoubleUniformRange(random, 0.5, 30.0);
for(unsigned int r(0); r < 100; r++)
{
uint32_t nU32 = RandomUint32WeightedChoice(random, kLimit, weights);
EATEST_VERIFY(nU32 < kLimit);
}
}
}
//NOTICE:
//Need Paul to look at this.
//At times, getting values outside of the assertion range.
#if !defined(EA_PLATFORM_IPHONE)
// Do basic randomness testing.
// Just because a random number generator passes known basic tests
// doesn't mean it doesn't have a major flaw.
{ // C runtime rand() test, provided for comparison.
int nErrorCountCRand(0); //We don't want to report these as part of our test.
rt_init(false);
for(int i(0); i < 100000; i++)
{
uint8_t nRandom = (uint8_t)(rand() & UINT8_MAX);
rt_add(&nRandom, sizeof(nRandom));
}
// See the rt_end documentation for detailed explanations
// of what each of these metrics mean.
double r_ent, r_chisq, r_mean, r_montepicalc, r_scc;
rt_end(&r_ent, &r_chisq, &r_mean, &r_montepicalc, &r_scc);
if(r_ent < 7.8)
nErrorCountCRand++;
else if(r_chisq < 200)
nErrorCountCRand++;
else if(r_mean < 127.2 || r_mean > 127.9)
nErrorCountCRand++;
else if(r_montepicalc < 3.11 || r_montepicalc > 3.17)
nErrorCountCRand++;
else if(r_scc > 0.01)
nErrorCountCRand++;
}
{ // RandomLinearCongruential test
RandomLinearCongruential random;
rt_init(false);
for(int i(0); i < 100000; i++)
{
uint32_t nRandom = random.RandomUint32Uniform();
rt_add(&nRandom, sizeof(nRandom));
}
// See the rt_end documentation for detailed explanations
// of what each of these metrics mean.
double r_ent, r_chisq, r_mean, r_montepicalc, r_scc;
rt_end(&r_ent, &r_chisq, &r_mean, &r_montepicalc, &r_scc);
EATEST_VERIFY(r_ent >= 7.8);
//EATEST_VERIFY(r_chisq >= 200); Disabled until we can figure out why it occasionally fails.
//EATEST_VERIFY(r_mean >= 127.2 && r_mean < 127.9); Disabled until we can figure out why it occasionally fails.
EATEST_VERIFY(r_montepicalc >= 3.11 && r_montepicalc < 3.17);
EATEST_VERIFY(r_scc <= 0.01);
}
{ // RandomMersenneTwister test
RandomMersenneTwister random;
rt_init(false);
for(int i(0); i < 100000; i++)
{
uint32_t nRandom = random.RandomUint32Uniform();
rt_add(&nRandom, sizeof(nRandom));
}
// See the rt_end documentation for detailed explanations
// of what each of these metrics mean.
double r_ent, r_chisq, r_mean, r_montepicalc, r_scc;
rt_end(&r_ent, &r_chisq, &r_mean, &r_montepicalc, &r_scc);
EATEST_VERIFY(r_ent >= 7.8);
//EATEST_VERIFY(r_chisq >= 200); Disabled until we can figure out why it occasionally fails.
//EATEST_VERIFY(r_mean >= 127.2 && r_mean < 127.9); Disabled until we can figure out why it occasionally fails.
EATEST_VERIFY(r_montepicalc >= 3.11 && r_montepicalc < 3.17);
EATEST_VERIFY(r_scc <= 0.01);
}
#endif
{ // RandomMersenneTwister seed serialization test.
RandomMersenneTwister rmt;
uint32_t seedArray[RandomMersenneTwister::kSeedArrayCount * 2];
uint32_t rand1, rand2;
unsigned size;
size = rmt.GetSeed(seedArray, RandomMersenneTwister::kSeedArrayCount);
EATEST_VERIFY(size == RandomMersenneTwister::kSeedArrayCount);
rand1 = rmt.RandomUint32Uniform();
rmt.RandomUint32Uniform();
rmt.SetSeed(seedArray, size);
rand2 = rmt.RandomUint32Uniform();
EATEST_VERIFY(rand1 == rand2);
size = rmt.GetSeed(seedArray, RandomMersenneTwister::kSeedArrayCount * 2);
EATEST_VERIFY(size == RandomMersenneTwister::kSeedArrayCount);
rand1 = rmt.RandomUint32Uniform();
rmt.RandomUint32Uniform();
rmt.SetSeed(seedArray, size);
rand2 = rmt.RandomUint32Uniform();
EATEST_VERIFY(rand1 == rand2);
size = rmt.GetSeed(seedArray, RandomMersenneTwister::kSeedArrayCount / 2);
EATEST_VERIFY(size == RandomMersenneTwister::kSeedArrayCount / 2);
rand1 = rmt.RandomUint32Uniform();
rmt.RandomUint32Uniform();
rmt.SetSeed(seedArray, size);
// We can't test for equality or inequality of rand1 and rand2
// This is just a pathological test.
size = rmt.GetSeed(seedArray, 0);
EATEST_VERIFY(size == 0);
rand1 = rmt.RandomUint32Uniform();
rmt.RandomUint32Uniform();
rmt.SetSeed(seedArray, size);
rand2 = rmt.RandomUint32Uniform();
EATEST_VERIFY(rand1 != rand2); // They should be different (actually one out of 4 billion times they shouldn't be) because we didn't read the entire state, but only half of it.
}
{
#if defined(EA_PLATFORM_DESKTOP) && !defined(EA_DEBUG) // Do this test only on fast machines, as it's compute-intensive.
// Range tests with FakeIncrementingRandom
const size_t sizes[] = { 2, 5, 10 };
eastl::vector<uint32_t> countBuckets(sizes[EAArrayCount(sizes) - 1], 0);
for(size_t a = 0; a < EAArrayCount(sizes); a++)
{
size_t s = sizes[a];
FakeIncrementingRandom fir;
eastl::fill(countBuckets.begin(), countBuckets.end(), 0);
for(uint64_t i = 0, iEnd = UINT64_C(0x100000000) / s * s; i < iEnd; i++)
{
if((i % 0x10000000) == 0)
EA::UnitTest::Report("."); // Keepalive output.
uint32_t b = EA::StdC::RandomLimit(fir, static_cast<uint32_t>(s));
countBuckets[b]++;
}
for(eastl_size_t b = 1, c = countBuckets[0]; b < s; b++)
{
if(countBuckets[b] != c)
{
EATEST_VERIFY(countBuckets[b] == c);
EA::UnitTest::Report("Random distribution result buckets for limit of %I32u:\n ", (uint32_t)s);
for(eastl_size_t bb = 0, bbEnd = s; bb < bbEnd; bb++)
EA::UnitTest::Report("%I32u%s", (uint32_t)countBuckets[bb], ((bb % 16) == 15) ? "\n" : " ");
EA::UnitTest::Report("\n");
break;
}
}
EA::UnitTest::Report(".\n"); // Keep alive output.
}
#endif
}
// Write out files suitable for the DieHard test suite.
// The version of DieHard that this author most recently
// worked with requires 8404992 bytes of data in a file.
// A copy of DieHard.exe should accompany this test.
// Currently, you drag a file onto it to get the results
// of the test. In the future we can implement the entire
// test within this file. It is about 3500 lines of code
// and would require some massaging to make it work
// smoothly with a unit testing system.
return nErrorCount;
}
///////////////////////////////////////////////////////////////////////////////
// Ent Chi-Squared functions
//
// Home:
// http://www.fourmilab.ch/random/
// License:
// This software is in the public domain. Permission to use, copy, modify,
// and distribute this software and its documentation for any purpose and
// without fee is hereby granted, without any conditions or restrictions.
// This software is provided "as is" without express or implied warranty.
///////////////////////////////////////////////////////////////////////////////
//
// Entropy
// The information density of the contents of the file, expressed as a
// number of bits per character. The results above, which resulted from
// processing an image file compressed with JPEG, indicate that the
// file is extremely dense in information--essentially random.
// Hence, compression of the file is unlikely to reduce its size.
// By contrast, the C source code of the program has entropy of about
// 4.9 bits per character, indicating that optimal compression of the
// file would reduce its size by 38%. [Hamming, pp. 104-108]
//
// Chi-square Test
// The chi-square test is the most commonly used test for the randomness
// of data, and is extremely sensitive to errors in pseudorandom sequence
// generators. The chi-square distribution is calculated for the stream
// of bytes in the file and expressed as an absolute number and a
// percentage which indicates how frequently a truly random sequence
// would exceed the value calculated. We interpret the percentage as the
// degree to which the sequence tested is suspected of being non-random.
// If the percentage is greater than 99% or less than 1%, the sequence is
// almost certainly not random. If the percentage is between 99% and 95%
// or between 1% and 5%, the sequence is suspect. Percentages between 90%
// and 95% and 5% and 10% indicate the sequence is "almost suspect".
// Note that our JPEG file, while very dense in information, is far from
// random as revealed by the chi-square test.
//
// Applying this test to the output of various pseudorandom sequence
// generators is interesting. The low-order 8 bits returned by the
// standard Unix rand() function, for example, yields:
// Chi square distribution for 500000 samples is 0.01, and randomly
// would exceed this value 99.99 percent of the times.
//
// While an improved generator [Park & Miller] reports:
// Chi square distribution for 500000 samples is 212.53, and randomly
// would exceed this value 95.00 percent of the times.
//
// Thus, the standard Unix generator (or at least the low-order bytes
// it returns) is unacceptably non-random, while the improved generator
// is much better but still sufficiently non-random to cause concern for
// demanding applications. Contrast both of these software generators
// with the chi-square result of a genuine random sequence created by
// timing radioactive decay events.
// Chi square distribution for 32768 samples is 237.05, and randomly
// would exceed this value 75.00 percent of the times.
//
// See [Knuth, pp. 35-40] for more information on the chi-square test.
// An interactive chi-square calculator is available at this site.
//
// Arithmetic Mean
// This is simply the result of summing the all the bytes (bits if the -b
// option is specified) in the file and dividing by the file length.
// If the data are close to random, this should be about 127.5 (0.5 for -b
// option output). If the mean departs from this value, the values are
// consistently high or low.
//
// Monte Carlo Value for Pi
// Each successive sequence of six bytes is used as 24 bit X and Y
// co-ordinates within a square. If the distance of the randomly-generated
// point is less than the radius of a circle inscribed within the square,
// the six-byte sequence is considered a "hit". The percentage of hits can
// be used to calculate the value of Pi. For very large streams
// (this approximation converges very slowly), the value will approach the
// correct value of Pi if the sequence is close to random. A 32768 byte
// file created by radioactive decay yielded:
// Monte Carlo value for Pi is 3.139648438 (error 0.06 percent).
//
// Serial Correlation Coefficient
// This quantity measures the extent to which each byte in the file
// depends upon the previous byte. For random sequences, this value
// (which can be positive or negative) will, of course, be close to zero.
// A non-random byte stream such as a C program will yield a serial
// correlation coefficient on the order of 0.5. Wildly predictable data
// such as uncompressed bitmaps will exhibit serial correlation coefficients
// approaching 1. See [Knuth, pp. 64-65] for more details.
///////////////////////////////////////////////////////////////////////////////
#define RFALSE 0
#define RTRUE 1
#define BINARY_MODE RTRUE
#define BYTE_MODE RFALSE
#define MONTEN 6 /* Bytes used as Monte Carlo co-ordinates. This should be no more bits than the mantissa of your "double" floating point type. */
#define log2of10 3.32192809488736234787
static int binary = RFALSE; /* Treat input as a bitstream */
static long ccount[256]; /* Bins to count occurrences of values */
static long totalc = 0; /* Total bytes counted */
static double prob[256]; /* Probabilities per bin for entropy */
static int mp, sccfirst;
static unsigned int monte[MONTEN];
static long inmont, mcount;
static double cexp, incirc, montex, montey, montepi, scc, sccun, sccu0, scclast, scct1, scct2, scct3, ent, chisq, datasum;
/* LOG2 -- Calculate log to the base 2 */
static double Local_log2(double x)
{
return log2of10 * log10(x);
}
/* RT_INIT -- Initialise random test counters. Call with BINARY_MODE or BYTE_MODE */
void rt_init(int binmode)
{
int i;
binary = binmode; /* Set binary / byte mode */
/* Initialise for calculations */
ent = 0.0; /* Clear entropy accumulator */
chisq = 0.0; /* Clear Chi-Square */
datasum = 0.0; /* Clear sum of bytes for arithmetic mean */
mp = 0; /* Reset Monte Carlo accumulator pointer */
mcount = 0; /* Clear Monte Carlo tries */
inmont = 0; /* Clear Monte Carlo inside count */
incirc = 65535.0 * 65535.0; /* In-circle distance for Monte Carlo */
sccfirst = RTRUE; /* Mark first time for serial correlation */
scct1 = scct2 = scct3 = 0.0; /* Clear serial correlation terms */
incirc = pow(pow(256.0, (double) (MONTEN / 2)) - 1, 2.0);
for (i = 0; i < 256; i++) {
ccount[i] = 0;
}
totalc = 0;
}
/* RT_ADD -- Add one or more bytes to accumulation. */
void rt_add(void* buf, int bufl)
{
unsigned char* bp =(unsigned char*)buf;
int oc, c, bean;
while (bean = 0, (bufl-- > 0))
{
oc = *bp++;
do {
if (binary) {
c = !!(oc & 0x80);
}
else {
c = oc;
}
ccount[c]++; /* Update counter for this bin */
totalc++;
/* Update inside / outside circle counts for Monte Carlo computation of PI */
if (bean == 0) {
monte[mp++] = (unsigned int)oc; /* Save character for Monte Carlo */
if (mp >= MONTEN) { /* Calculate every MONTEN character */
int mj;
mp = 0;
mcount++;
montex = montey = 0;
for (mj = 0; mj < MONTEN / 2; mj++) {
montex = (montex * 256.0) + monte[mj];
montey = (montey * 256.0) + monte[(MONTEN / 2) + mj];
}
if ((montex * montex + montey * montey) <= incirc) {
inmont++;
}
}
}
/* Update calculation of serial correlation coefficient */
sccun = (double)c;
if (sccfirst) {
sccfirst = RFALSE;
scclast = 0;
sccu0 = sccun;
}
else {
scct1 = scct1 + scclast * sccun;
}
scct2 = scct2 + sccun;
scct3 = scct3 + (sccun * sccun);
scclast = sccun;
oc <<= 1;
} while (binary && (++bean < 8));
}
}
/* RT_END -- Complete calculation and return results. */
void rt_end(double* r_ent, double* r_chisq, double* r_mean,
double* r_montepicalc, double* r_scc)
{
int i;
double a;
/* Complete calculation of serial correlation coefficient */
scct1 = scct1 + scclast * sccu0;
scct2 = scct2 * scct2;
scc = totalc * scct3 - scct2;
if (scc == 0.0) {
scc = -100000;
}
else {
scc = (totalc * scct1 - scct2) / scc;
}
/* Scan bins and calculate probability for each bin and Chi-Square distribution */
cexp = totalc / (binary ? 2.0 : 256.0); /* Expected count per bin */
for (i = 0; i < (binary ? 2 : 256); i++) {
prob[i] = (double) ccount[i] / totalc;
a = ccount[i] - cexp;
chisq = chisq + (a * a) / cexp;
datasum += ((double) i) * ccount[i];
}
/* Calculate entropy */
for (i = 0; i < (binary ? 2 : 256); i++) {
if (prob[i] > 0.0) {
ent += prob[i] * Local_log2(1 / prob[i]);
}
}
/* Calculate Monte Carlo value for PI from percentage of hits within the circle */
montepi = 4.0 * (((double) inmont) / mcount);
/* Return results through arguments */
*r_ent = ent;
*r_chisq = chisq;
*r_mean = datasum / totalc;
*r_montepicalc = montepi;
*r_scc = scc;
}
///////////////////////////////////////////////////////////////////////////////
#if 0
static double get_double()
{
return 1.0;
}
static double CalculateSqrm(double a, double b)
{
return ((a - b) * (a - b)) / b;
}
static double CalculatePhi(double x)
{
static const double v[15] =
{
1.2533141373155, .6556795424187985, .4213692292880545,
.3045902987101033, .2366523829135607, .1928081047153158,
.1623776608968675, .1401041834530502, .1231319632579329,
.1097872825783083, .09902859647173193, .09017567550106468,
.08276628650136917, .0764757610162485, .07106958053885211
};
// Local variables
double cphi, a, b, h;
double z, sum, pwr;
int i, j;
if (fabs(x) > 7.0)
{
if (x >= 0.0)
return 1.0;
return 0.0;
}
if (x>=0.0)
cphi = 0.0;
else
cphi = 1.0;
j = (int) (fabs(x) + 0.5);
j = std::min<int>(j, 14);
z = (double) j;
h = fabs(x) - z;
a = v[j];
b = z * a - 1.0;
pwr = 1.0;
sum = a + h * b;
for (i = 2; i <= (24-j); i += 2)
{
a = (a + z * b) / i;
b = (b + z * a) / (i + 1);
pwr *= h * h;
sum += pwr * (a + h * b);
}
cphi = sum * exp(x * -0.5 * x - 0.918938533204672);
if (x < 0.0)
return cphi;
return 1.0 - cphi;
}
static double CalculateChisq(double x, int n)
{
// System generated locals
double ret_val;
// Local variables
double d;
long i, l;
double s, t;
double xmin;
if (x <= 0.0)
return 0.0;
if (n > 20)
{
t = (pow( x / n, 0.33333) - 1.0 + 0.22222 / n) / sqrt(0.22222 / n);
return CalculatePhi(std::min(t, 8.0));
}
l = 4 - n % 2;
d = (double) std::min(1, n / 3);
ret_val = 0.0;
for (i = l; i <= n; i += 2)
{
d = d * x / (i - 2);
ret_val += d;
}
xmin = std::min(x * 0.5, 50.0);
if (l == 3)
{
s = sqrt( xmin );
return CalculatePhi(s/0.7071068) - exp(-xmin) * 0.564189 * ret_val / s;
}
return 1.0 - exp(-xmin) * (ret_val + 1.0);
}
///////////////////////////////////////////////////////////////////////////////
// TestCraps
//
// This is the Craps test. It plays 200,000 games of craps, finds
// the number of wins and the number of throws necessary to end
// each game. The number of wins should be (very close to) a
// normal with mean 200000p and variance 200000p(1 - p), with
// p = 244 / 495. Throws necessary to complete the game can vary
// from 1 to infinity, but counts for all > 21 are lumped with 21.
// A chi-square test is made on the #-of-throws cell counts.
// Each 32-bit integer from the test file provides the value for
// the throw of a die, by floating to [0, 1), multiplying by 6
// and taking 1 plus the integer part of the result.
//
static void TestCraps(double& pvalueWins, double& pvalueThrows)
{
static long nt[22];
static double e[22];
double t;
double pwins;
double av; // Expected win count.
double sd;
double ex;
double sum;
long ng;
long gc;
long nwins; // Actual win count.
double pthrows;
int nthrows;
int point;
int i, m, k;
e[1] = 1.0 / 3.0;
sum = e[1];
for (k = 2; k <= 20; ++k)
{
e[k] = ( pow(27.0/36.0, (double) k-2) * 27.0 +
pow(26.0/36.0, (double) k-2) * 40.0 +
pow(25.0/36.0, (double) k-2) * 55.0 ) / 648.0;
sum += e[k];
}
e[21] = 1.0 - sum;
ng = 200000;
nwins = 0;
for (i = 1; i <= 21; ++i)
nt[i] = 0;
for (gc = 1; gc <= ng; ++gc)
{
point = (int)(get_double() * 6.0) + (int)(get_double() * 6.0) + 2;
nthrows = 1;
if ((point == 7) || (point == 11))
++nwins;
else if ((point != 2) && (point != 3) && (point != 12))
{
for(;;)
{
++nthrows;
k = (int)(get_double() * 6.0) + (int)(get_double() * 6.0) + 2;
if (k == 7)
break;
if (k == point)
{
++nwins;
break;
}
}
}
m = std::min<int>(21, nthrows);
++nt[m];
}
av = ng * 244.0 / 495.0;
sd = sqrt(av * 251.0 / 495.0);
t = (nwins - av) / sd;
//dprintf(" Results of craps test for %s\n", filename);
//dprintf(" No. of wins: Observed Expected\n");
//dprintf(" %9ld %11.2f\n", nwins, av);
pwins = CalculatePhi(t);
//dprintf(" %8ld= No. of wins, z-score=%6.3f pvalue=%7.5f\n", nwins, t, pwins);
//dprintf(" Analysis of Throws-per-Game:\n");
sum = 0.0;
for (i = 1; i <= 21; ++i)
{
ex = ng * e[i];
sum += CalculateSqrm((double)nt[i], ex);
}
pthrows = CalculateChisq(sum, 20);
//dprintf(" Chisq=%7.2f for 20 degrees of freedom, p=%8.5f\n", sum, pthrows);
//dprintf(" Throws Observed Expected Chisq Sum\n");
//sum = 0.0;
//for (i = 1; i <= 21; ++i)
//{
// ex = ng * e[i];
// t = sqrm((double)nt[i], ex);
// sum += t;
//
// dprintf("%19d %8ld %10.1f %7.3f %8.3f\n", i, nt[i], ex, t, sum);
//}
//save_pvalue(pwins);
//save_pvalue(pthrows);
//dprintf(" SUMMARY FOR %s\n", filename);
//dprintf(" p-value for no. of wins:%8.6f\n", pwins);
//dprintf(" p-value for throws/game:%8.6f\n", pthrows);
pvalueWins = pwins;
pvalueThrows = pthrows;
}
#endif
#ifdef _MSC_VER
#pragma warning(pop)
#endif