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124 lines
3.6 KiB
C
124 lines
3.6 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilot Math Utilities
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* @{
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* @addtogroup Reuseable math functions
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* @{
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*
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* @file mathmisc.h
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief Reuseable math functions
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*
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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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, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef MATHMISC_H
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#define MATHMISC_H
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#include <math.h>
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#include <stdint.h>
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// returns min(boundary1,boundary2) if val<min(boundary1,boundary2)
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// returns max(boundary1,boundary2) if val>max(boundary1,boundary2)
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// returns val if min(boundary1,boundary2)<=val<=max(boundary1,boundary2)
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static inline float boundf(float val, float boundary1, float boundary2)
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{
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if (boundary1 > boundary2) {
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if (!(val >= boundary2)) {
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return boundary2;
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} else if (!(val <= boundary1)) {
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return boundary1;
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}
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} else {
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if (!(val >= boundary1)) {
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return boundary1;
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} else if (!(val <= boundary2)) {
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return boundary2;
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}
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}
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return val;
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}
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static inline float squaref(float x)
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{
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return x * x;
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}
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static inline float vector_lengthf(float *vector, const uint8_t dim)
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{
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float length = 0.0f;
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for (int t = 0; t < dim; t++) {
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length += squaref(vector[t]);
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}
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return sqrtf(length);
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}
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static inline void vector_normalizef(float *vector, const uint8_t dim)
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{
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float length = vector_lengthf(vector, dim);
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if (length <= 0.0f || isnan(length)) {
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return;
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}
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for (int t = 0; t < dim; t++) {
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vector[t] /= length;
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}
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}
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typedef struct pointf {
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float x;
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float y;
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} pointf;
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// Returns the y value, given x, on the line passing through the points p0 and p1.
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static inline float y_on_line(float x, const pointf *p0, const pointf *p1)
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{
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// Setup line y = m * x + b.
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const float dY1 = p1->y - p0->y;
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const float dX1 = p1->x - p0->x;
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const float m = dY1 / dX1; // == dY0 / dX0 == (p0.y - b) / (p0.x - 0.0f) ==>
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const float b = p0->y - m * p0->x;
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// Get the y value on the line.
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return m * x + b;
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}
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// Returns the y value, given x, on the curve defined by the points array.
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// The fist and last line of the curve extends beyond the first resp. last points.
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static inline float y_on_curve(float x, const pointf points[], int num_points)
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{
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// Find the two points x is within.
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// If x is smaller than the first point's x value, use the first line of the curve.
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// If x is larger than the last point's x value, user the last line of the curve.
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int end_point = num_points - 1;
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for (int i = 1; i < num_points; i++) {
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if (x < points[i].x) {
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end_point = i;
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break;
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}
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}
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// Find the y value on the selected line.
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return y_on_line(x, &points[end_point - 1], &points[end_point]);
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}
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#endif /* MATHMISC_H */
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