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This commit is contained in:
Timur A. Fatkhullin 2025-03-04 18:58:21 +03:00
parent 6d1806689e
commit 6cc00381d1
1 changed files with 68 additions and 3 deletions
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71
cxx/mount_astrom.h
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@ -22,10 +22,75 @@ concept mcc_scalar_or_simd_c = xsimd::is_batch<T>::value || std::is_arithmetic_v
namespace mcc::astro
{
// modified Julian date
template <traits::mcc_scalar_or_simd_c T>
int mcc_julday(const std::chrono::utc_clock::time_point& greg_time, T& mjd)
// modified Julian date (based on ERFA eraCal2jd)
// template <traits::mcc_scalar_or_simd_c T>
static int mcc_julday(const std::chrono::system_clock::time_point& start_time,
const std::chrono::system_clock::duration& step,
std::vector<double, xsimd::default_allocator<double>>& mjd)
{
if (mjd.empty()) {
return -100;
}
using namespace std::literals::chrono_literals;
auto dd = std::chrono::floor<std::chrono::days>(start_time);
std::chrono::year_month_day ymd{dd};
static constexpr std::chrono::year MIN_YEAR = -4799y;
if (ymd.year() < MIN_YEAR) {
return -1;
}
if (!ymd.month().ok()) {
return -2;
}
// my = (im - 14) / 12;
// iypmy = (long) (iy + my);
int64_t my = -(14 - (unsigned)ymd.month()) / 12;
int64_t iypmy = (int)ymd.year() + my;
// (1461L * (iypmy + 4800L)) / 4L
// + (367L * (long) (im - 2 - 12 * my)) / 12L
// - (3L * ((iypmy + 4900L) / 100L)) / 4L
// + (long) id - 2432076L
// integer part of result MJD
int64_t mjd_int = 1461LL * (iypmy + 480LL) / 4LL +
(367LL * ((int64_t)(unsigned)ymd.month() - 2LL - 12LL * my)) / 12LL -
(3LL * (iypmy + 4900LL) / 100LL) / 4LL + (int64_t)(unsigned)ymd.day() - 2432076LL;
constexpr double nanosec = 1.0 / 24.0 / 3600.0 / 1.0E-9; // 1 nanosecond in days
double mjd_float = static_cast<double>(mjd_int) +
std::chrono::duration_cast<std::chrono::nanoseconds>(start_time - dd).count() * nanosec;
double d_step = std::chrono::duration_cast<std::chrono::nanoseconds>(step).count() * nanosec;
constexpr size_t reg_size = xsimd::batch<double>::size;
size_t vec_size = mjd.size() - mjd.size() % reg_size;
xsimd::batch<double> res_reg{mjd_float};
xsimd::batch<double> step_reg = [d_step]<size_t... Is>(std::index_sequence<Is...>) {
return xsimd::batch<double>{(Is * d_step)...};
}(std::make_index_sequence<reg_size>{});
// vectorized part
size_t i = 0;
for (; i < vec_size; i += vec_size) {
res_reg += step_reg;
res_reg.store_aligned(mjd.data() + i);
}
// scalar part
for (size_t j = i; j < mjd.size(); ++j) {
mjd[j] = mjd_float + j * d_step;
}
return 0;
}
template <traits::mcc_scalar_or_simd_c T, typename CT, typename DT>