# ARTS built-in documentation server

## Workspace Method MatrixCBR

### Description

Sets a matrix to hold cosmic background radiation (CBR).
The CBR is assumed to be un-polarized and Stokes components 2-4
are zero. Number of Stokes components, that equals the number
of columns in the created matrix, is determined by stokes_dim.
The number of rows in the created matrix equals the length of the
given frequency vector.
The cosmic radiation is modelled as blackbody radiation for the
temperature given by the global constant COSMIC_BG_TEMP, set in
the file constants.cc. The frequencies are taken from the generic
input vector.
The standard definition, in ARTS, of the Planck function is
followed and the unit of the returned data is W/(m3 * Hz * sr).

**Authors: **Patrick Eriksson

### Synopsis

### Variables

GOUT | output | (Matrix) | Variable to initialize. |

IN | stokes_dim | (Index) | The dimensionality of the Stokes vector (1-4). |

GIN | f | (Vector) | Frequency vector. |