diff --git a/gtsam/basis/Chebyshev2.h b/gtsam/basis/Chebyshev2.h index 4c3542d56..55bb39488 100644 --- a/gtsam/basis/Chebyshev2.h +++ b/gtsam/basis/Chebyshev2.h @@ -51,27 +51,30 @@ class GTSAM_EXPORT Chebyshev2 : public Basis { using Parameters = Eigen::Matrix; using DiffMatrix = Eigen::Matrix; - /// 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; }