class pypose.randn_RxSO3(*lsize, sigma=1.0, **kwargs)[source]

Returns RxSO3_type LieTensor filled with the Exponential map of the random rxso3_type LieTensor. The rxso3_type LieTensor is generated using randn_rxso3().

\[\mathrm{data}[*, :] = \mathrm{Exp}([\delta_x, \delta_y, \delta_z, \log s]), \]

where rotation \([\delta_x, \delta_y, \delta_z]\) is generated using pypose.randn_so3() with standard deviation \(\sigma_r\), scale \(\log s\) is generated from a normal distribution \(\mathcal{N}(0, \sigma_s)\), and \(\mathrm{Exp}()\) is the Exponential map. Note that standard deviations \(\sigma_r\) and \(\sigma_s\) are specified by sigma (\(\sigma\)), where \(\sigma = (\sigma_r, \sigma_s)\).

  • lsize (int...) – a sequence of integers defining the lshape of the output tensor. Can be a variable number of arguments or a collection like a list or tuple.

  • sigma (float or (float...), optional) – standard deviation (\(\sigma_r\), and \(\sigma_s\)) for the two normal distribution. Default: 1.0.

  • requires_grad (bool, optional) – If autograd should record operations on the returned tensor. Default: False.

  • generator (torch.Generator, optional) – a pseudorandom number generator for sampling

  • dtype (torch.dtype, optional) – the desired data type of returned tensor. Default: None. If None, uses a global default (see torch.set_default_tensor_type()).

  • layout (torch.layout, optional) – the desired layout of returned Tensor. Default: torch.strided.

  • device (torch.device, optional) – the desired device of returned tensor. Default: “None”. If None, uses the current device for the default tensor type (see torch.set_default_tensor_type()). Device will be the CPU for CPU tensor types and the current CUDA device for CUDA tensor types.


a RxSO3_type LieTensor

Return type



The parameter \(\sigma\) can either be:

  • a single float – in which all the elements in the RxSO3_type share the same sigma, i.e., \(\sigma_{\rm{r}}\) = \(\sigma_{\rm{s}}\) = \(\sigma\).

  • a tuple of two floats – in which case, the specific sigmas for the two parts are assigned independently, i.e., \(\sigma\) = (\(\sigma_{\rm{r}}\), \(\sigma_{\rm{s}}\)).


For \(\sigma = (\sigma_r, \sigma_s)\)

>>> pp.randn_RxSO3(2, sigma=(1.0, 2.0))
RxSO3Type LieTensor:
tensor([[-0.1929, -0.0141,  0.2859,  0.9385,  4.5562],
        [-0.2871,  0.0134, -0.2903,  0.9128,  3.1044]])


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