70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
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/**
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* Marlin 3D Printer Firmware
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* Copyright (c) 2020 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 <https://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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#include "../inc/MarlinConfig.h"
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#if NEED_LSF
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#include "least_squares_fit.h"
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#include <math.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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const float RN = 1.0f / N,
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xbar = lsf->xbar * RN,
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ybar = lsf->ybar * RN,
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zbar = lsf->zbar * RN,
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x2bar = lsf->x2bar * RN - sq(xbar),
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y2bar = lsf->y2bar * RN - sq(ybar),
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xybar = lsf->xybar * RN - xbar * ybar,
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yzbar = lsf->yzbar * RN - ybar * zbar,
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xzbar = lsf->xzbar * RN - xbar * zbar,
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DD = x2bar * y2bar - sq(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 = (yzbar * xybar - xzbar * y2bar) / DD;
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lsf->B = (xzbar * xybar - yzbar * x2bar) / DD;
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lsf->D = -(zbar + lsf->A * xbar + lsf->B * ybar);
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return 0;
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}
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#endif // NEED_LSF
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