C++ vd::size方法代码示例

	double average( vd v)
	{
		vd::iterator it;
		double sum = 0.0;

		if ( v.size() == 0) return(0.0);

		for(it = v.begin(); it < v.end(); ++it)
			sum += *it;

		return(sum/v.size());
	}

//a1x1+a2x2+a3=0
//b1x1+b2x2+b3=0
vctr solve(vd &a, vd &b)
{
    assert(a.size()==b.size()&&a.size()==3);
    if(fabs(b[0])>fabs(a[0]))swap(a,b);
    assert(fabs(a[0])>EPS);
    double k=b[0]/a[0];
    rep(i,3)b[i]-=a[i]*k;
    assert(fabs(b[1])>EPS);
    double x2=-b[2]/b[1];
    double x1=-(a[2]+a[1]*x2)/a[0];
    return vctr(x1,x2);
}

void constructPoints(const vector<Edge> &edges, const vd &mesh,
    vector<Point> &points, vvi &edge2point) {
  points.clear();
  for (int x = 2; x <= 8; x += 2) {
    for (int y = 2; y <= 8; y += 2) {
      for (int z = 2; z <= 8; z += 2) {
        D3 p(x, y, z);
        if (isOneOfEndPoint(p, edges)) {
          points.push_back(Point(p));
          for (int i = 0; i < edges.size(); i++) {
            if (edges[i].src == p) {
              addPoint(points, edge2point, i);
            } else if (edges[i].dst == p) {
              addPoint(points, edge2point, i);
            }
          }
        }
      }
    }
  }
  for (int i = 0; i < edges.size(); i++) {
    D3 p = edges[i].src;
    D3 v = edges[i].dst - edges[i].src;
    for (int j = 0; j < mesh.size(); j++) {
      points.push_back(Point(p + mesh[j]*v));
      addPoint(points, edge2point, i);
    }
  }
}

	double stddev( vd v, double avg)
	{
		vd::iterator it;
		double sumSq = SumSquaredDifferences(v, avg);

		return( stddev(sumSq,v.size()) );
	}

void printTask(const vvd& a, const vd& b, const vd& c, const std::string& filename = "task.txt")
{
    size_t n = c.size();
    size_t m = a.size();
    std::ofstream out(filename);
    for (size_t i = 0; i < n; ++i)
    {
        auto& t = c[i];
        if (std::abs(t) < EPS)
        {
            continue;
        }
        if (t > 0)
        {
            out << "+\t" << t;
        }
        if (t < 0)
        {
            out << "-\t" << -t;
        }
        out << " * x" << i + 1 << "\t";
    }
    out << "-----> MAX\n";
    for (size_t i = 0; i < m; ++i)
    {
        out << "x" << n + i + 1 << "\t=\t" << b[i] << "\t";
        for (size_t j = 0; j < n; ++j)
        {
            auto t = -a[i][j];
            if (std::abs(t) < EPS)
            {
                continue;
            }
            if (t > 0)
            {
                out << "+\t" << t;
            }
            if (t < 0)
            {
                out << "-\t" << -t;
            }
            out << " * x" << j + 1 << "\t";
        }
        out << endl;
    }
}

double pcet::operator()(const vd& v) {
  double xn1 = v[1],pn1 = v[2],xn2 = v[3],pn2 = v[4],qr = v[5],pr = v[6];
  double n1=e.n(xn1,pn1),n2=e.n(xn2,pn2);
  double h_bath=0.0;
  for (size_t i = 7; i < v.size(); ++(++i)) {
    size_t ib=(i-7)/2;
    double mw2=bp.m*pow(bw[ib],2);
    h_bath+= v[i+1]*v[i+1]*0.5/bp.m
      + mw2*0.5*pow((v[i]+n1*bc[ib]/mw2),2);
  }
  double h11 = sp.eps_r + sp.w_r*sp.w_r*sp.m*pow((qr-sp.qr_initial),2)*0.5;
  double h22 = sp.eps_k + sp.w_k*sp.w_k*sp.m*pow((qr-sp.qr_initial),2)*0.5;
  double h12 = sp.delta;
  double h_avg= (h11+h22)*0.5;
  double h_delta= h11-h22;
  return pr*pr*0.5/sp.m+
    h_avg+
    h_delta*(n1-n2)*0.5+
    sp.delta*(xn1*xn2+pn1*pn2) + h_bath;
    //2*delta*sqrt((n1+e.n_shift)*(n2+e.n_shift))*(xn1*xn2+pn1*pn2); ///> TODO
}

void print(const vd &a){rep(i,a.size())printf("%.2lf%c",a[i],i==a.size()-1?'\n':' ');}

void zero_out(vd & v, vd & u, int j)
{
	if(zero(u[j])) return;
	double r = u[j] / v[j];
	range(k, j, v.size()) u[k] -= r * v[k];
}

void normalise(vd & v, int j)
{
	double x = v[j];
	range(k, j, v.size()) v[k] /= x;
}

void printResult(vd &v){
	int n = v.size();
	printf("Xn:    Yn:\n");
	for(int i=0; i<n; i++)
		printf("%.2f   %.4f\n", v[i].first, v[i].second);
}

 vd fwht_rev(vd& a) {
     vd res = fwht(a);
     F0R(i,sz(res)) res[i] /= a.size();
     return res;
 }

//shortest path from a node n to every other node: 
//this is for any graphs even ones that have negative weights -- can detect negative cycles
//for every vertex, relax E times
//as an optimization we use a queue to store vertices that changed
//and relax paths only from that queue
//to detect negative loops can check if node n gets updated on any the n-th iteration
int BellmanFordMoore(const graphtp & g, vd & D, int src)     
{
    int comparisons = 0;
    vi visited(g.size());
    std::vector<edge> P(g.size()); //parent node for node e.to is e.from

    for(vd::iterator it = D.begin(); it != D.end(); ++it) 
        *it = INFINITY;
    D[src] = 0;

    si lastupdated;

    //keep a queue (set) of vertices (nodes) that were updated last time around
    //do the relaxation V times 
    for(size_t i = 0; i < g.size(); i++) {
        lastupdated.insert(i);
    }


    //without optimization loop would be: for(int i = 0; i < g.size(); i++) 
    size_t counter = 0;
    while(!lastupdated.empty()) {
        counter++;
        si newlast;
        //visit and relax all edges (two for loopxs needed to visit all edges)
        for(si::iterator jt = lastupdated.begin();jt != lastupdated.end(); jt++)
        {
            int v = *jt;
            out("next to work on is %d\n", v);
            for(ve::const_iterator it = g[v].begin(); it != g[v].end(); ++it)
            {
                float dist = D[v] + it->weight;
                assert(v == it->from && "not the same node");
                if(D[it->to] > dist) { //this is the relaxation step
                    out("counter %d, it->to %d\n", counter, it->to);
                    if(counter >= g.size()) { 
                        //we should not update a node in a stage greater than sz
                        printf("negative cycles exists distance %d to %d is %f\n", v, it->to, dist);
                        //need to trace back from P[v]
                        //printSP(P, it->to, v);
                        printSP(P, v, it->to);
                        printf("\n");
                        return -1;
                    }
                    D[it->to] = dist;
                    P[it->to] = *it;
                    newlast.insert(it->to); //track which changed
                    out("new distance %d to %d is %f\n", v, it->to, dist);
                }
            }
        }
        lastupdated = newlast;
    }

    for(size_t i = 0; i < D.size(); i++) {
        printf("%d -> %d sp=%.2f ", src, i, D[i]);
        printSP(P, i, src);
        printf("\n");
    }
    out("comparisons %d\n", comparisons);
    return 0;
}

vi bitstream(vd in)
{
	vi out(in.size());
	for (int n=0; n<in.size(); n++) {out[n]=(copysign(1,in[n])+1)/2;}
	return out;
}