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LSST Data Management Base Package
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Classes | Functions
lsst::meas::astrom::detail Namespace Reference

Classes

class  BinomialMatrix
 A class that computes binomial coefficients up to a certain power. More...
 

Functions

int computePackedOffset (int order)
 Compute the index of the first coefficient with the given order in a packed 2-d polynomial coefficient array.
 
int computePackedSize (int order)
 Compute this size of a packed 2-d polynomial coefficient array.
 
void computePowers (Eigen::VectorXd &r, double x)
 Fill an array with integer powers of x, so \($r[n] == r^n\).
 
Eigen::VectorXd computePowers (double x, int n)
 Return an array with integer powers of x, so \($r[n] == r^n\).
 

Function Documentation

◆ computePackedOffset()

int lsst::meas::astrom::detail::computePackedOffset ( int order)
inline

Compute the index of the first coefficient with the given order in a packed 2-d polynomial coefficient array.

This defines the ordering as

[(0,0), (0,1), (1,0), (0,2), (1,1), (2,0), ...]

(or the same with indices swapped).

Definition at line 45 of file polynomialUtils.h.

45{ return (order * (order + 1)) / 2; }
table::Key< int > order

◆ computePackedSize()

int lsst::meas::astrom::detail::computePackedSize ( int order)
inline

Compute this size of a packed 2-d polynomial coefficient array.

Definition at line 50 of file polynomialUtils.h.

50{ return computePackedOffset(order + 1); }
int computePackedOffset(int order)
Compute the index of the first coefficient with the given order in a packed 2-d polynomial coefficien...

◆ computePowers() [1/2]

Eigen::VectorXd lsst::meas::astrom::detail::computePowers ( double x,
int n )

Return an array with integer powers of x, so \($r[n] == r^n\).

When multiple powers are needed, this should be signficantly faster than repeated calls to std::pow().

Definition at line 40 of file polynomialUtils.cc.

40 {
41 Eigen::VectorXd r(n + 1);
42 computePowers(r, x);
43 return r;
44}
void computePowers(Eigen::VectorXd &r, double x)
Fill an array with integer powers of x, so .

◆ computePowers() [2/2]

void lsst::meas::astrom::detail::computePowers ( Eigen::VectorXd & r,
double x )

Fill an array with integer powers of x, so \($r[n] == r^n\).

When multiple powers are needed, this should be signficantly faster than repeated calls to std::pow().

Definition at line 33 of file polynomialUtils.cc.

33 {
34 r[0] = 1.0;
35 for (int i = 1; i < r.size(); ++i) {
36 r[i] = r[i - 1] * x;
37 }
38}