| 2 | #include <string.h> |
| 3 | |
| 4 | void thomas(double * const a, double * const b, double * const c, |
| 5 | double * const x, const size_t size) { |
| 6 | |
| 7 | double y[size]; |
| 8 | memset(y, 0, size * sizeof(double)); |
| 9 | |
| 10 | y[0] = c[0] / b[0]; |
| 11 | x[0] = x[0] / b[0]; |
| 12 | |
| 13 | for (size_t i = 1; i < size; ++i) { |
| 14 | double scale = 1.0 / (b[i] - a[i] * y[i - 1]); |
| 15 | y[i] = c[i] * scale; |
| 16 | x[i] = (x[i] - a[i] * x[i - 1]) * scale; |
| 17 | } |
| 18 | |
| 19 | for (size_t i = size - 2; i < size - 1; --i) { |
| 20 | x[i] -= y[i] * x[i + 1]; |
| 21 | } |
| 22 | } |
| 23 | |
| 24 | int main() { |
| 25 | double a[] = {0.0, 2.0, 3.0}; |