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/**
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* Marlin 3D Printer Firmware
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* Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
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*
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* Based on Sprinter and grbl.
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* Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/**
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* Least Squares Best Fit by Roxy and Ed Williams
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*
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* This algorithm is high speed and has a very small code footprint.
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* Its results are identical to both the Iterative Least-Squares published
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* earlier by Roxy and the QR_SOLVE solution. If used in place of QR_SOLVE
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* it saves roughly 10K of program memory. It also does not require all of
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* coordinates to be present during the calculations. Each point can be
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* probed and then discarded.
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*
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*/
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#include "MarlinConfig.h"
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#if ENABLED(AUTO_BED_LEVELING_UBL) || ENABLED(AUTO_BED_LEVELING_LINEAR)
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#include "macros.h"
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#include <math.h>
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#include "least_squares_fit.h"
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int finish_incremental_LSF(struct linear_fit_data *lsf) {
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const float N = lsf->N;
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if (N == 0.0)
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return 1;
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lsf->xbar /= N;
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lsf->ybar /= N;
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lsf->zbar /= N;
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lsf->x2bar = lsf->x2bar / N - sq(lsf->xbar);
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lsf->y2bar = lsf->y2bar / N - sq(lsf->ybar);
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lsf->z2bar = lsf->z2bar / N - sq(lsf->zbar);
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lsf->xybar = lsf->xybar / N - lsf->xbar * lsf->ybar;
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lsf->yzbar = lsf->yzbar / N - lsf->ybar * lsf->zbar;
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lsf->xzbar = lsf->xzbar / N - lsf->xbar * lsf->zbar;
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const float DD = lsf->x2bar * lsf->y2bar - sq(lsf->xybar);
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if (ABS(DD) <= 1e-10 * (lsf->max_absx + lsf->max_absy))
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return 1;
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lsf->A = (lsf->yzbar * lsf->xybar - lsf->xzbar * lsf->y2bar) / DD;
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lsf->B = (lsf->xzbar * lsf->xybar - lsf->yzbar * lsf->x2bar) / DD;
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lsf->D = -(lsf->zbar + lsf->A * lsf->xbar + lsf->B * lsf->ybar);
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return 0;
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}
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#endif // AUTO_BED_LEVELING_UBL || ENABLED(AUTO_BED_LEVELING_LINEAR)
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