本文整理汇总了C++中TVectorD::Use方法的典型用法代码示例。如果您正苦于以下问题：C++ TVectorD::Use方法的具体用法？C++ TVectorD::Use怎么用？C++ TVectorD::Use使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类TVectorD的用法示例。
在下文中一共展示了TVectorD::Use方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: solveLinear
void solveLinear(Double_t eps = 1.e-12)
{
cout << "Perform the fit y = c0 + c1 * x in four different ways" << endl;
const Int_t nrVar = 2;
const Int_t nrPnts = 4;
Double_t ax[] = {0.0,1.0,2.0,3.0};
Double_t ay[] = {1.4,1.5,3.7,4.1};
Double_t ae[] = {0.5,0.2,1.0,0.5};
// Make the vectors 'Use" the data : they are not copied, the vector data
// pointer is just set appropriately
TVectorD x; x.Use(nrPnts,ax);
TVectorD y; y.Use(nrPnts,ay);
TVectorD e; e.Use(nrPnts,ae);
TMatrixD A(nrPnts,nrVar);
TMatrixDColumn(A,0) = 1.0;
TMatrixDColumn(A,1) = x;
cout << " - 1. solve through Normal Equations" << endl;
const TVectorD c_norm = NormalEqn(A,y,e);
cout << " - 2. solve through SVD" << endl;
// numerically preferred method
// first bring the weights in place
TMatrixD Aw = A;
TVectorD yw = y;
for (Int_t irow = 0; irow < A.GetNrows(); irow++) {
TMatrixDRow(Aw,irow) *= 1/e(irow);
yw(irow) /= e(irow);
}
TDecompSVD svd(Aw);
Bool_t ok;
const TVectorD c_svd = svd.Solve(yw,ok);
cout << " - 3. solve with pseudo inverse" << endl;
const TMatrixD pseudo1 = svd.Invert();
TVectorD c_pseudo1 = yw;
c_pseudo1 *= pseudo1;
cout << " - 4. solve with pseudo inverse, calculated brute force" << endl;
TMatrixDSym AtA(TMatrixDSym::kAtA,Aw);
const TMatrixD pseudo2 = AtA.Invert() * Aw.T();
TVectorD c_pseudo2 = yw;
c_pseudo2 *= pseudo2;
cout << " - 5. Minuit through TGraph" << endl;
TGraphErrors *gr = new TGraphErrors(nrPnts,ax,ay,0,ae);
TF1 *f1 = new TF1("f1","pol1",0,5);
gr->Fit("f1","Q");
TVectorD c_graph(nrVar);
c_graph(0) = f1->GetParameter(0);
c_graph(1) = f1->GetParameter(1);
// Check that all 4 answers are identical within a certain
// tolerance . The 1e-12 is somewhat arbitrary . It turns out that
// the TGraph fit is different by a few times 1e-13.
Bool_t same = kTRUE;
same &= VerifyVectorIdentity(c_norm,c_svd,0,eps);
same &= VerifyVectorIdentity(c_norm,c_pseudo1,0,eps);
same &= VerifyVectorIdentity(c_norm,c_pseudo2,0,eps);
same &= VerifyVectorIdentity(c_norm,c_graph,0,eps);
if (same)
cout << " All solutions are the same within tolerance of " << eps << endl;
else
cout << " Some solutions differ more than the allowed tolerance of " << eps << endl;
}