forked from OSchip/llvm-project
				
			
		
			
				
	
	
		
			342 lines
		
	
	
		
			9.8 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			342 lines
		
	
	
		
			9.8 KiB
		
	
	
	
		
			C++
		
	
	
	
//===----------------------------------------------------------------------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <random>
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// template<class RealType = double>
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// class piecewise_linear_distribution
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// template<class _URNG> result_type operator()(_URNG& g);
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#include <iostream>
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#include <random>
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#include <vector>
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#include <iterator>
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#include <numeric>
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#include <cassert>
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template <class T>
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inline
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T
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sqr(T x)
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{
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    return x*x;
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}
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double
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f(double x, double a, double m, double b, double c)
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{
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    return a + m*(sqr(x) - sqr(b))/2 + c*(x-b);
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}
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int main()
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{
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    {
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        typedef std::piecewise_linear_distribution<> D;
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        typedef D::param_type P;
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        typedef std::mt19937_64 G;
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        G g;
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        double b[] = {10, 14, 16, 17};
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        double p[] = {0, 1, 1, 0};
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        const size_t Np = sizeof(p) / sizeof(p[0]) - 1;
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        D d(b, b+Np+1, p);
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        const int N = 1000000;
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        std::vector<D::result_type> u;
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        for (int i = 0; i < N; ++i)
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        {
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            D::result_type v = d(g);
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            assert(d.min() <= v && v < d.max());
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            u.push_back(v);
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        }
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        std::sort(u.begin(), u.end());
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        int kp = -1;
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        double a;
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        double m;
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        double bk;
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        double c;
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        std::vector<double> areas(Np);
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        double S = 0;
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        for (int i = 0; i < areas.size(); ++i)
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        {
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            areas[i] = (p[i]+p[i+1])*(b[i+1]-b[i])/2;
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            S += areas[i];
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        }
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        for (int i = 0; i < areas.size(); ++i)
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            areas[i] /= S;
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        for (int i = 0; i < Np+1; ++i)
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            p[i] /= S;
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        for (int i = 0; i < N; ++i)
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        {
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            int k = std::lower_bound(b, b+Np+1, u[i]) - b - 1;
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            if (k != kp)
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            {
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                a = 0;
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                for (int j = 0; j < k; ++j)
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                    a += areas[j];
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                m = (p[k+1] - p[k]) / (b[k+1] - b[k]);
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                bk = b[k];
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                c = (b[k+1]*p[k] - b[k]*p[k+1]) / (b[k+1] - b[k]);
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                kp = k;
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            }
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            assert(std::abs(f(u[i], a, m, bk, c) - double(i)/N) < .001);
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        }
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    }
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    {
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        typedef std::piecewise_linear_distribution<> D;
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        typedef D::param_type P;
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        typedef std::mt19937_64 G;
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        G g;
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        double b[] = {10, 14, 16, 17};
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        double p[] = {0, 0, 1, 0};
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        const size_t Np = sizeof(p) / sizeof(p[0]) - 1;
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        D d(b, b+Np+1, p);
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        const int N = 1000000;
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        std::vector<D::result_type> u;
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        for (int i = 0; i < N; ++i)
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        {
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            D::result_type v = d(g);
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            assert(d.min() <= v && v < d.max());
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            u.push_back(v);
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        }
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        std::sort(u.begin(), u.end());
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        int kp = -1;
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        double a;
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        double m;
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        double bk;
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        double c;
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        std::vector<double> areas(Np);
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        double S = 0;
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        for (int i = 0; i < areas.size(); ++i)
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        {
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            areas[i] = (p[i]+p[i+1])*(b[i+1]-b[i])/2;
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            S += areas[i];
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        }
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        for (int i = 0; i < areas.size(); ++i)
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            areas[i] /= S;
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        for (int i = 0; i < Np+1; ++i)
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            p[i] /= S;
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        for (int i = 0; i < N; ++i)
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        {
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            int k = std::lower_bound(b, b+Np+1, u[i]) - b - 1;
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            if (k != kp)
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            {
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                a = 0;
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                for (int j = 0; j < k; ++j)
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                    a += areas[j];
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                m = (p[k+1] - p[k]) / (b[k+1] - b[k]);
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                bk = b[k];
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                c = (b[k+1]*p[k] - b[k]*p[k+1]) / (b[k+1] - b[k]);
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                kp = k;
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            }
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            assert(std::abs(f(u[i], a, m, bk, c) - double(i)/N) < .001);
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        }
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    }
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    {
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        typedef std::piecewise_linear_distribution<> D;
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        typedef D::param_type P;
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        typedef std::mt19937_64 G;
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        G g;
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        double b[] = {10, 14, 16, 17};
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        double p[] = {1, 0, 0, 0};
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        const size_t Np = sizeof(p) / sizeof(p[0]) - 1;
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        D d(b, b+Np+1, p);
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        const int N = 1000000;
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        std::vector<D::result_type> u;
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        for (int i = 0; i < N; ++i)
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        {
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            D::result_type v = d(g);
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            assert(d.min() <= v && v < d.max());
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            u.push_back(v);
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        }
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        std::sort(u.begin(), u.end());
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        int kp = -1;
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        double a;
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        double m;
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        double bk;
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        double c;
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        std::vector<double> areas(Np);
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        double S = 0;
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        for (int i = 0; i < areas.size(); ++i)
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        {
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            areas[i] = (p[i]+p[i+1])*(b[i+1]-b[i])/2;
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            S += areas[i];
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        }
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        for (int i = 0; i < areas.size(); ++i)
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            areas[i] /= S;
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        for (int i = 0; i < Np+1; ++i)
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            p[i] /= S;
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        for (int i = 0; i < N; ++i)
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        {
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            int k = std::lower_bound(b, b+Np+1, u[i]) - b - 1;
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            if (k != kp)
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            {
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                a = 0;
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                for (int j = 0; j < k; ++j)
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                    a += areas[j];
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                m = (p[k+1] - p[k]) / (b[k+1] - b[k]);
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                bk = b[k];
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                c = (b[k+1]*p[k] - b[k]*p[k+1]) / (b[k+1] - b[k]);
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                kp = k;
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            }
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            assert(std::abs(f(u[i], a, m, bk, c) - double(i)/N) < .001);
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        }
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    }
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    {
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        typedef std::piecewise_linear_distribution<> D;
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        typedef D::param_type P;
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        typedef std::mt19937_64 G;
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        G g;
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        double b[] = {10, 14, 16};
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        double p[] = {0, 1, 0};
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        const size_t Np = sizeof(p) / sizeof(p[0]) - 1;
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        D d(b, b+Np+1, p);
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        const int N = 1000000;
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        std::vector<D::result_type> u;
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        for (int i = 0; i < N; ++i)
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        {
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            D::result_type v = d(g);
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            assert(d.min() <= v && v < d.max());
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            u.push_back(v);
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        }
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        std::sort(u.begin(), u.end());
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        int kp = -1;
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        double a;
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        double m;
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        double bk;
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        double c;
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        std::vector<double> areas(Np);
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        double S = 0;
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        for (int i = 0; i < areas.size(); ++i)
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        {
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            areas[i] = (p[i]+p[i+1])*(b[i+1]-b[i])/2;
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            S += areas[i];
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        }
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        for (int i = 0; i < areas.size(); ++i)
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            areas[i] /= S;
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        for (int i = 0; i < Np+1; ++i)
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            p[i] /= S;
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        for (int i = 0; i < N; ++i)
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        {
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            int k = std::lower_bound(b, b+Np+1, u[i]) - b - 1;
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            if (k != kp)
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            {
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                a = 0;
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                for (int j = 0; j < k; ++j)
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                    a += areas[j];
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                m = (p[k+1] - p[k]) / (b[k+1] - b[k]);
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                bk = b[k];
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                c = (b[k+1]*p[k] - b[k]*p[k+1]) / (b[k+1] - b[k]);
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                kp = k;
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            }
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            assert(std::abs(f(u[i], a, m, bk, c) - double(i)/N) < .001);
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        }
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    }
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    {
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        typedef std::piecewise_linear_distribution<> D;
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        typedef D::param_type P;
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        typedef std::mt19937_64 G;
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        G g;
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        double b[] = {10, 14};
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        double p[] = {1, 1};
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        const size_t Np = sizeof(p) / sizeof(p[0]) - 1;
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        D d(b, b+Np+1, p);
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        const int N = 1000000;
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        std::vector<D::result_type> u;
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        for (int i = 0; i < N; ++i)
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        {
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            D::result_type v = d(g);
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            assert(d.min() <= v && v < d.max());
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            u.push_back(v);
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        }
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        std::sort(u.begin(), u.end());
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        int kp = -1;
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        double a;
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        double m;
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        double bk;
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        double c;
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        std::vector<double> areas(Np);
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        double S = 0;
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        for (int i = 0; i < areas.size(); ++i)
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        {
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            areas[i] = (p[i]+p[i+1])*(b[i+1]-b[i])/2;
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            S += areas[i];
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        }
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        for (int i = 0; i < areas.size(); ++i)
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            areas[i] /= S;
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        for (int i = 0; i < Np+1; ++i)
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            p[i] /= S;
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        for (int i = 0; i < N; ++i)
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        {
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            int k = std::lower_bound(b, b+Np+1, u[i]) - b - 1;
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            if (k != kp)
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            {
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                a = 0;
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                for (int j = 0; j < k; ++j)
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                    a += areas[j];
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                m = (p[k+1] - p[k]) / (b[k+1] - b[k]);
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                bk = b[k];
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                c = (b[k+1]*p[k] - b[k]*p[k+1]) / (b[k+1] - b[k]);
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                kp = k;
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            }
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            assert(std::abs(f(u[i], a, m, bk, c) - double(i)/N) < .001);
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        }
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    }
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    {
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        typedef std::piecewise_linear_distribution<> D;
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        typedef D::param_type P;
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        typedef std::mt19937_64 G;
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        G g;
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        double b[] = {10, 14, 16, 17};
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        double p[] = {25, 62.5, 12.5, 0};
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        const size_t Np = sizeof(p) / sizeof(p[0]) - 1;
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        D d(b, b+Np+1, p);
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        const int N = 1000000;
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        std::vector<D::result_type> u;
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        for (int i = 0; i < N; ++i)
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        {
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            D::result_type v = d(g);
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            assert(d.min() <= v && v < d.max());
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            u.push_back(v);
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        }
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        std::sort(u.begin(), u.end());
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        int kp = -1;
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        double a;
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        double m;
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        double bk;
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        double c;
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        std::vector<double> areas(Np);
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        double S = 0;
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        for (int i = 0; i < areas.size(); ++i)
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        {
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            areas[i] = (p[i]+p[i+1])*(b[i+1]-b[i])/2;
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            S += areas[i];
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        }
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        for (int i = 0; i < areas.size(); ++i)
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            areas[i] /= S;
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        for (int i = 0; i < Np+1; ++i)
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            p[i] /= S;
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        for (int i = 0; i < N; ++i)
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        {
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            int k = std::lower_bound(b, b+Np+1, u[i]) - b - 1;
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            if (k != kp)
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            {
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                a = 0;
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                for (int j = 0; j < k; ++j)
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                    a += areas[j];
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                m = (p[k+1] - p[k]) / (b[k+1] - b[k]);
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                bk = b[k];
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                c = (b[k+1]*p[k] - b[k]*p[k+1]) / (b[k+1] - b[k]);
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                kp = k;
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            }
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            assert(std::abs(f(u[i], a, m, bk, c) - double(i)/N) < .001);
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        }
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    }
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}
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