Devuan fork of gpsd
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 ``````/* * Unit test for matrix-algebra code * * Check examples computed at * http://www.elektro-energetika.cz/calculations/matreg.php * * This file is Copyright (c) 2010 by the GPSD project * SPDX-License-Identifier: BSD-2-clause */ #include #include #include #include #include #include "../compiler.h" #include "../matrix.h" static struct { double mat[4][4]; double inv[4][4]; } inverses[] = { /* identity matrix is self-inverse */ { .mat = {{1,0,0,0}, {0,1,0,0}, {0,0,1,0}, {0,0,0,1}}, .inv = {{1,0,0,0}, {0,1,0,0}, {0,0,1,0}, {0,0,0,1}}, }, /* inverse of a diagonal matrix has reciprocal values */ { .mat = {{10,0,0,0}, {0,10,0,0}, {0,0,10,0}, {0,0,0,10}}, .inv = {{0.1,0,0,0}, {0,0.1,0,0}, {0,0,0.1,0}, {0,0,0,0.1}}, }, /* random values with asymmetrical off-diagonal elements */ { .mat = {{1,0,0,0}, {0,1,0,-2}, {0, 2,1,-4}, {0,0,0,1}}, .inv = {{1,0,0,0}, {0,1,0, 2}, {0,-2,1, 0}, {0,0,0,1}}, }, { .mat = {{6,-4,1,-3},{-4,7,3,2},{1,3,6,-4},{-3,2,-4,6}}, .inv = {{14,34,-40,-31},{34,84,-99,-77},{-40,-99,117,91},{-31,-77,91,71}}, }, }; static void dump(const char *label, double m[4][4]) { printf("%s:\n", label); printf("%f, %f, %f, %f\n", m[0][0], m[0][1], m[0][2], m[0][3]); printf("%f, %f, %f, %f\n", m[1][0], m[1][1], m[1][2], m[1][3]); printf("%f, %f, %f, %f\n", m[2][0], m[2][1], m[2][2], m[2][3]); printf("%f, %f, %f, %f\n", m[3][0], m[3][1], m[3][2], m[3][3]); } static bool check_diag(int n, double a[4][4], double b[4][4]) { #define approx(x, y) (fabs(x - y) < 0.0001) if (approx(b[0][0], a[0][0]) && approx(b[1][1], a[1][1]) && approx(b[2][2], a[2][2]) && approx(b[3][3], a[3][3])) return true; dump("a", a); dump("b", b); printf("Test %d residuals: %f %f %f %f\n", n, b[0][0] - a[0][0], b[1][1] - a[1][1], b[2][2] - a[2][2], b[3][3] - a[3][3] ); return true; } int main(int argc UNUSED, char *argv[] UNUSED) { unsigned int i; for (i = 0; i < sizeof(inverses) / sizeof(inverses[0]); i++) { double inverse[4][4]; if (!matrix_invert(inverses[i].mat, inverse)) { printf("Vanishing determinant in test %u\n", i); } if (!check_diag(i, inverse, inverses[i].inv)) break; } printf("Matrix-algebra regression test succeeded\n"); exit(0); }``````