| l_fn(x, s) | |
| if model_s1 is None: | |
| x_s1 = ( | |
| expand_dims(sigma_s1 / sigma_s, dims) * x | |
| - expand_dims(alpha_s1 * phi_11, dims) * model_s | |
| ) | |
| model_s1 = self.model_fn(x_s1, s1) | |
| x_s2 = ( | |
| expand_dims(sigma_s2 / sigma_s, dims) * x | |
| - expand_dims(alpha_s2 * phi_12, dims) * model_s | |
| + r2 / r1 * expand_dims(alpha_s2 * phi_22, dims) * (model_s1 - model_s) | |
| ) | |
| model_s2 = self.model_fn(x_s2, s2) | |
| if solver_type == 'dpm_solver': | |
| x_t = ( | |
| expand_dims(sigma_t / sigma_s, dims) * x | |
| - expand_dims(alpha_t * phi_1, dims) * model_s | |
| + (1. / r2) * expand_dims(alpha_t * phi_2, dims) * (model_s2 - model_s) | |
| ) | |
| elif solver_type == 'taylor': | |
| D1_0 = (1. / r1) * (model_s1 - model_s) | |
| D1_1 = (1. / r2) * (model_s2 - model_s) | |
| D1 = (r2 * D1_0 - r1 * D1_1) / (r2 - r1) | |
| D2 = 2. * (D1_1 - D1_0) / (r2 - r1) | |
| x_t = ( | |
| expand_dims(sigma_t / sigma_s, dims) * x | |
| - expand_dims(alpha_t * phi_1, dims) * model_s | |
| + expand_dims(alpha_t * phi_2, dims) * D1 | |
| - expand_dims(alpha_t * phi_3, dims) * D2 | |
| ) |