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| 1 | /* |
| 2 | * matrix.h - 2D matrix operations |
| 3 | * |
| 4 | * Written 2010 by Werner Almesberger |
| 5 | * Copyright 2010 by Werner Almesberger |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | */ |
| 12 | |
| 13 | #ifndef MATRIX_H |
| 14 | #define MATRIX_H |
| 15 | |
| 16 | /* |
| 17 | * 2D transformation: |
| 18 | * |
| 19 | * x' = x*a[0][0]+y*a[0][1]+b[0] |
| 20 | * y' = x*a[1][0]+y*a[1][1]+b[1] |
| 21 | */ |
| 22 | |
| 23 | |
| 24 | struct matrix { |
| 25 | double a[2][2]; |
| 26 | double b[2]; |
| 27 | }; |
| 28 | |
| 29 | |
| 30 | void matrix_identity(struct matrix *m); |
| 31 | void matrix_invert(const double m[2][2], double res[2][2]); |
| 32 | void matrix_mult(double a[2][2], double b[2][2], double res[2][2]); |
| 33 | void matrix_multv(const double v[2], double m[2][2], double res[2]); |
| 34 | void matrix_copy(double from[2][2], double to[2][2]); |
| 35 | |
| 36 | |
| 37 | static inline void matrix_map(int x, int y, const struct matrix *m, |
| 38 | double *res_x, double *res_y) |
| 39 | { |
| 40 | *res_x = x*m->a[0][0]+y*m->a[0][1]+m->b[0]; |
| 41 | *res_y = x*m->a[1][0]+y*m->a[1][1]+m->b[1]; |
| 42 | |
| 43 | } |
| 44 | |
| 45 | #endif /* !MATRIX_H */ |
| 46 |
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