expand_bound

sionna.phy.utils.expand_bound(f: Callable, bound: torch.Tensor, side: str, step_expand: float = 2.0, max_n_iter: int = 100, precision: str | None = None, **kwargs) → torch.Tensor

Expands the left (right, respectively) search interval end point until the function f becomes positive (negative, resp.)

Parameters:

• f (Callable) – Generic function handle that takes batched inputs and returns batched outputs. Applies a different decreasing univariate function to each of its inputs. Must accept input batches of the same shape as left and right.

• bound (torch.Tensor) – […], torch.float. Left (if side is ‘left’) or right (if side is ‘right’) end point of the initial search interval, for each batch.

• side (str) – ‘left’ | ‘right’. See bound.

• step_expand (float) – Geometric progression factor at which the bound is expanded. Must be higher than 1.

• max_n_iter (int) – Maximum number of iterations.

• precision (str | None) – Precision used for internal calculations and outputs. If set to None, precision is used.

• kwargs – Additional arguments for function f.

Outputs:

bound – […], torch.float. Final value of expanded bound.

Examples

import torch
from sionna.phy.utils.numerics import expand_bound

# Define a decreasing univariate function of x
def f(x):
    return -x + 1.0

# Expand right bound until f becomes negative
bound = torch.tensor(0.5)
result = expand_bound(f, bound, side='right', step_expand=2.0)
print(result)