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overload the Chebyshev2::Point method to reduce duplication

release/4.3a0
Varun Agrawal 2023-09-18 23:05:25 -04:00
parent 2a386f8631
commit b2efd64d2b
1 changed files with 15 additions and 12 deletions
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27
gtsam/basis/Chebyshev2.h
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@ -51,27 +51,30 @@ class GTSAM_EXPORT Chebyshev2 : public Basis<Chebyshev2> {
using Parameters = Eigen::Matrix<double, /*Nx1*/ -1, 1>;
using DiffMatrix = Eigen::Matrix<double, /*NxN*/ -1, -1>;
/// Specific Chebyshev point
static double Point(size_t N, int j) {
/**
* @brief Specific Chebyshev point, within [a,b] interval.
* Default interval is [-1, 1]
*
* @param N The degree of the polynomial
* @param j The index of the Chebyshev point
* @param a Lower bound of interval (default: -1)
* @param b Upper bound of interval (default: 1)
* @return double
*/
static double Point(size_t N, int j, double a = -1, double b = 1) {
assert(j >= 0 && size_t(j) < N);
const double dtheta = M_PI / (N > 1 ? (N - 1) : 1);
// We add -PI so that we get values ordered from -1 to +1
// sin(- M_PI_2 + dtheta*j); also works
return cos(-M_PI + dtheta * j);
}
/// Specific Chebyshev point, within [a,b] interval
static double Point(size_t N, int j, double a, double b) {
assert(j >= 0 && size_t(j) < N);
const double dtheta = M_PI / (N - 1);
// We add -PI so that we get values ordered from -1 to +1
// sin(-M_PI_2 + dtheta*j); also works
return a + (b - a) * (1. + cos(-M_PI + dtheta * j)) / 2;
}
/// All Chebyshev points
static Vector Points(size_t N) {
Vector points(N);
for (size_t j = 0; j < N; j++) points(j) = Point(N, j);
for (size_t j = 0; j < N; j++) {
points(j) = Point(N, j);
}
return points;
}