Blame ImathTest/testRandom.cpp

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///////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
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// Digital Ltd. LLC
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// 
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// All rights reserved.
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// 
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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// *       Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// *       Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// *       Neither the name of Industrial Light & Magic nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission. 
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// 
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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///////////////////////////////////////////////////////////////////////////
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#include <testRandom.h>
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#include "ImathRandom.h"
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#include "ImathVec.h"
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#include "ImathFun.h"
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#include <iostream>
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#include <iomanip>
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#include <assert.h>
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using namespace std;
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using IMATH_INTERNAL_NAMESPACE::abs;
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namespace {
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void
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testErand48 ()
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{
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    //
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    // Our implementation of erand48(), nrand48(), etc.
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    // assumes that sizeof (unsigned short) == 2.
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    //
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    assert (sizeof (unsigned short) == 2);
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    //
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    // starting with a given seed, erand48() and nrand48()
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    // must generate the same sequence as the standard
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    // Unix/Linux functions.
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    //
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    unsigned short state[3];
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    state[0] = 0;
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    state[1] = 1;
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    state[2] = 2;
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    assert (abs (IMATH_INTERNAL_NAMESPACE::erand48 (state) - 0.671004) < 0.00001);
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    assert (abs (IMATH_INTERNAL_NAMESPACE::erand48 (state) - 0.786905) < 0.00001);
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    assert (abs (IMATH_INTERNAL_NAMESPACE::erand48 (state) - 0.316850) < 0.00001);
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    assert (abs (IMATH_INTERNAL_NAMESPACE::erand48 (state) - 0.384870) < 0.00001);
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    assert (abs (IMATH_INTERNAL_NAMESPACE::erand48 (state) - 0.854650) < 0.00001);
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    assert (IMATH_INTERNAL_NAMESPACE::nrand48 (state) == 0x4f4e8cb0);
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    assert (IMATH_INTERNAL_NAMESPACE::nrand48 (state) == 0x063e864b);
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    assert (IMATH_INTERNAL_NAMESPACE::nrand48 (state) == 0x2d10f1dd);
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    assert (IMATH_INTERNAL_NAMESPACE::nrand48 (state) == 0x1aadc122);
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    assert (IMATH_INTERNAL_NAMESPACE::nrand48 (state) == 0x1836a71f);
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    assert (state[0] == 0x2a42);
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    assert (state[1] == 0x4e3e);
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    assert (state[2] == 0x306d);
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}
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template <class Rand>
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void
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testGenerator ()
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{
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    //
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    // Test if the values, and the differences between
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    // successive values, are evenly distributed.
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    //
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    const int N = 10;
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    const int M = 100000;
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    int values[N + 1];
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    int diffs[2 * N + 3];
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    int *v = &values[0];
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    int *d = &diffs[N + 2];
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    for (int i = 0; i <= N; ++i)
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	v[i] = 0;
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    for (int i = -N; i <= N; ++i)
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	d[i] = 0;
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    Rand rand (0);
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    float previous = 0;
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    for (int i = 0; i < M * N; ++i)
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    {
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	float r = rand.nextf (0.0, 1.0);
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	float diff = r - previous;
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	previous = r;
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	v[int (r * N)] += 1;
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	d[IMATH_INTERNAL_NAMESPACE::floor (diff * N + 0.5)] += 1;
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    }
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    cout << "  values" << endl;
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    for (int i = 0; i < N; ++i)
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    {
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	// cout << setw (4) << i << ' ' << setw(6) << v[i] << ' ';
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	assert (abs (v[i] - M) < 0.01 * M);
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	// for (int j = 0; j < v[i] * 60 / M; ++j)
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	//      cout << '*';
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	// cout << endl;
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    }
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    assert (v[N] == 0);
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    cout << "  differences between successive values" << endl;
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    for (int i = -N; i <= N; ++i)
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    {
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	// cout << setw (4) << i << ' ' << setw (6) << d[i] << ' ';
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	assert (abs ((N - abs (i)) * M / N - d[i]) < 0.05 * M);
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	// for (int j = 0; j < d[i] * 60 / M; ++j)
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	//     cout << '*';
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	// cout << endl;
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    }
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    cout << "  range" << endl;
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    double rMin = 1.0;
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    double rMax = 0.0;
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    for (int i = 0; i <= 10000000; ++i)
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    {
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	double r = rand.nextf (0.0, 1.0);
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	if (rMin > r)
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	    rMin = r;
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	if (rMax < r)
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	    rMax = r;
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    }
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    assert (rMin < 0.0001 && rMax > 0.9999);
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    const double pow_2_60 = double (1073741824) * double (1073741824);
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    for (int i = 0; i <= 10000000; ++i)
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    {
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	double r0 = rand.nextf (-2.0, 3.0);
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	assert (r0 >= -2.0 && r0 <= 3.0);
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	double r1 = rand.nextf (-pow_2_60, 1);
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	assert (r1 >= -pow_2_60 && r1 <= 1);
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	double r2 = rand.nextf (-1, pow_2_60);
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	assert (r2 >= -1 && r2 <= pow_2_60);
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    }
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}
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template <class Rand>
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void
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testSolidSphere ()
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{
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    const int N = 10;
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    const int M = 10000;
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    int v[N + 1];
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    for (int i = 0; i <= N; ++i)
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	v[i] = 0;
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    Rand rand (0);
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    for (int i = 0; i < M * N; ++i)
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    {
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	IMATH_INTERNAL_NAMESPACE::V3f p = IMATH_INTERNAL_NAMESPACE::solidSphereRand<IMATH_INTERNAL_NAMESPACE::V3f> (rand);
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	float l = p.length();
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	v[IMATH_INTERNAL_NAMESPACE::floor (l * N)] += 1;
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	assert (l < 1.00001);
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    }
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    for (int i = 0; i < N; ++i)
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	assert (v[i] > 0);
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}
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template <class Rand>
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void
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testHollowSphere ()
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{
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    const int M = 100000;
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    Rand rand (0);
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    for (int i = 0; i < M; ++i)
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    {
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	IMATH_INTERNAL_NAMESPACE::V3f p = IMATH_INTERNAL_NAMESPACE::hollowSphereRand<IMATH_INTERNAL_NAMESPACE::V3f> (rand);
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	float l = p.length();
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	assert (abs (l - 1) < 0.00001);
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    }
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}
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} // namespace
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void
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testRandom ()
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{
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    cout << "Testing random number generators" << endl;
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    cout << "erand48(), nrand48()" << endl;
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    testErand48();
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    cout << "Rand32" << endl;
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    testGenerator<IMATH_INTERNAL_NAMESPACE::Rand32>();
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    cout << "Rand48" << endl;
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    testGenerator<IMATH_INTERNAL_NAMESPACE::Rand48>();
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    cout << "solidSphereRand()" << endl;
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    testSolidSphere<IMATH_INTERNAL_NAMESPACE::Rand32>();
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    cout << "hollowSphereRand()" << endl;
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    testHollowSphere<IMATH_INTERNAL_NAMESPACE::Rand32>();
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    cout << "ok\n" << endl;
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}