lsst.geom g096abc94f8+9702225f61
PolynomialFunction1d.cc
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1// -*- LSST-C++ -*-
2/*
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5 * (https://www.lsst.org).
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21 */
22
23#include <vector>
24
28
29
30namespace lsst { namespace geom { namespace polynomials {
31
33 auto const & basis = f.getBasis();
34 std::vector<SafeSum<double>> sums(basis.size());
35 double const s = basis.getScaling().getScale();
36 double const v = basis.getScaling().getShift();
37 double sn = 1; // s^n
38 BinomialMatrix binomial(basis.getNested().getOrder());
39 for (std::size_t n = 0; n < basis.size(); ++n, sn *= s) {
40 double vk = 1; // v^k
41 for (std::size_t k = 0; k <= n; ++k, vk *= v) {
42 sums[n - k] += sn*binomial(n, k)*f[n]*vk;
43 }
44 }
45 Eigen::VectorXd result = Eigen::VectorXd::Zero(basis.size());
46 for (std::size_t n = 0; n < basis.size(); ++n) {
47 result[n] = static_cast<double>(sums[n]);
48 }
49 return makeFunction1d(basis.getNested(), result);
50}
51
52}}} // namespace lsst::geom::polynomials
A class that computes binomial coefficients up to a certain power.
A 1-d function defined by a series expansion and its coefficients.
Definition: Function1d.h:42
Basis const & getBasis() const
Return the associated Basis1d object.
Definition: Function1d.h:98
Function1d< Basis > makeFunction1d(Basis const &basis, Eigen::VectorXd const &coefficients)
Create a Function1d of the appropriate type from a Basis1d and an Eigen object containing coefficient...
Definition: Function1d.h:144
PolynomialFunction1d simplified(ScaledPolynomialFunction1d const &f)
Calculate the standard polynomial function that is equivalent to a scaled standard polynomial functio...