|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
#include "FWCore/Utilities/interface/Exception.h"
#include "CondFormats/HcalObjects/interface/HcalChebyshevFunctor.h"
HcalChebyshevFunctor::HcalChebyshevFunctor() : xmin_(-1.0), xmax_(1.0), outOfRangeValue_(0.0) {}
HcalChebyshevFunctor::HcalChebyshevFunctor(const std::vector<double>& coeffs,
const double xmin,
const double xmax,
const double outOfRangeValue)
: coeffs_(coeffs), xmin_(xmin), xmax_(xmax), outOfRangeValue_(outOfRangeValue) {
if (xmin_ >= xmax_)
throw cms::Exception("In HcalChebyshevFunctor constructor: invalid interval specification");
}
double HcalChebyshevFunctor::operator()(const double y) const {
if (!(y >= xmin_ && y <= xmax_))
return outOfRangeValue_;
if (coeffs_.empty())
return 0.0;
const double x = 2.0 * (y - xmin_) / (xmax_ - xmin_) - 1.0;
const double* a = &coeffs_[0];
const double twox = 2.0 * x;
// Clenshaw recursion
double rp2 = 0.0, rp1 = 0.0, r = 0.0;
for (unsigned k = coeffs_.size() - 1; k > 0U; --k) {
r = twox * rp1 - rp2 + a[k];
rp2 = rp1;
rp1 = r;
}
return x * rp1 - rp2 + a[0];
}
BOOST_CLASS_EXPORT_IMPLEMENT(HcalChebyshevFunctor)
|