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- /**
- * Marlin 3D Printer Firmware
- * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
- *
- * Based on Sprinter and grbl.
- * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
- /**
- * Least Squares Best Fit by Roxy and Ed Williams
- *
- * This algorithm is high speed and has a very small code footprint.
- * Its results are identical to both the Iterative Least-Squares published
- * earlier by Roxy and the QR_SOLVE solution. If used in place of QR_SOLVE
- * it saves roughly 10K of program memory. It also does not require all of
- * coordinates to be present during the calculations. Each point can be
- * probed and then discarded.
- *
- */
-
- #include "../inc/MarlinConfig.h"
-
- #if ANY(AUTO_BED_LEVELING_UBL, AUTO_BED_LEVELING_LINEAR, Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
-
- #include "least_squares_fit.h"
-
- #include <math.h>
-
- int finish_incremental_LSF(struct linear_fit_data *lsf) {
-
- const float N = lsf->N;
-
- if (N == 0.0)
- return 1;
-
- lsf->xbar /= N;
- lsf->ybar /= N;
- lsf->zbar /= N;
- lsf->x2bar = lsf->x2bar / N - sq(lsf->xbar);
- lsf->y2bar = lsf->y2bar / N - sq(lsf->ybar);
- lsf->z2bar = lsf->z2bar / N - sq(lsf->zbar);
- lsf->xybar = lsf->xybar / N - lsf->xbar * lsf->ybar;
- lsf->yzbar = lsf->yzbar / N - lsf->ybar * lsf->zbar;
- lsf->xzbar = lsf->xzbar / N - lsf->xbar * lsf->zbar;
- const float DD = lsf->x2bar * lsf->y2bar - sq(lsf->xybar);
-
- if (ABS(DD) <= 1e-10 * (lsf->max_absx + lsf->max_absy))
- return 1;
-
- lsf->A = (lsf->yzbar * lsf->xybar - lsf->xzbar * lsf->y2bar) / DD;
- lsf->B = (lsf->xzbar * lsf->xybar - lsf->yzbar * lsf->x2bar) / DD;
- lsf->D = -(lsf->zbar + lsf->A * lsf->xbar + lsf->B * lsf->ybar);
- return 0;
- }
-
- #endif // AUTO_BED_LEVELING_UBL || ENABLED(AUTO_BED_LEVELING_LINEAR)
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