| def sgns(*args): | |
| for i in args: | |
| if i < 0: | |
| break | |
| else: | |
| return 1 | |
| for i in args: | |
| if i > 0: | |
| break | |
| else: | |
| return -1 | |
| return 0 | |
| def sq_func_sgn(a, b, c): | |
| r""" | |
| let f(x) = a+bx+cx^2, x \in [0, 1] | |
| :return: f(x)>=0? 1; f(x)<=0? -1; 0 | |
| """ | |
| f0 = a | |
| f1 = a + b + c | |
| fm = 0 | |
| if c != 0: | |
| x_m = -b / (2 * c) | |
| if 0 <= x_m <= 1: | |
| fm = a + b * x_m + c * x_m**2 | |
| return sgns(f0, f1, fm) | |
| def lin_func_sgn(a, b): | |
| return sgns(a, a + b) | |