# ARTS built-in documentation server

## Workspace Method covmat_seAddBlock

### Description

Add a block to the measurement covariance matrix covmat_se
This functions adds a given dense or sparse matrix as block to the covariance
matrix covmat_sx. The position of the block can be given by the generic
arguments ``i`` and ``j``. Note that diagonal blocks must be added in order starting from
in the top left corner. If an off-diagonal block is added it must have corresponding
existing blocks on the diagonal and these must be consistent with the dimensions
of the block. If ``i`` and ``j`` are not provided, the blok will be added
at the first free spot on the diagonal.

**Authors: **Simon Pfreundschuh

### Synopsis

### Variables

OUT+IN | covmat_se | (CovarianceMatrix) | Covariance matrix for observation uncertainties. |

GIN | block | (Matrix, Sparse) | The block to add to the covariance matrix |

GIN | i | (Index, Default: -1) | Index of a retrieval quantity. Must satisfy ``i`` <= ``j``. |

GIN | j | (Index, Default: -1) | Index of a retrieval quantity. Must satisfy ``i`` <= ``j``. |