
# Add (Gaussian white) wrapped noise

Add noise to the data, which is done by adding Gaussian noise and “wrapping” it to the $\mathbb S^n$, i.e. in $T_x\M$ of some data $x\in\M$ this function adds white Gaussian noise (componentwise) to a zero tangent vector and perform an exponential map $x_{\text{noisy}} = \exp_x(\eta)$, where $\eta$ is Gaussian noise on $\mathbb R^n$.

### Matlab Documentation

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% fn = addNoise(f,sigma) add Gaussian tangential noise to f w/ deviation sigma
%
% INPUT
%   f   : data on Sn
% sigma : standard deviation
%
% OUTPUT
%  fn  : noisy data
% ---
% Manifold-Valued Image Restoration Toolbox 1.0
% R. Bergmann ~ 2018-03-03