# ARTS built-in documentation server

## Workspace Method yDoublingMeanFocus

### Description

Focus in on y around some f_grid, then sets f_grid to
same focus
The algorithm will double the frequency spacing DF
steps away from F0, doubling it again DF steps away
from F0+DF, and so on until the end of the range.
The same happens but reversely towards F0-DF, ...
Inside these ranges, the values will be averaged
so that there's one value per original input
between F0-DF and F0+DF, 1 value per 2 original values
between F0+DF and F0+2*DF, and so on ever doubling the
number of original values per output value
F0 and DF are set inside the function to either the values
given by the user, or if they are non-positive as mean(f_grid)
and 10 * (f_grid[1] - f_grid[0]), respectively
Ignores NaNs and infinities in averaging calculations.

**Authors: **Richard Larsson

### Synopsis

yDoublingMeanFocus( | f_grid, y, f0, df ) |

### Variables

OUT+IN | f_grid | (Vector) | The frequency grid for monochromatic pencil beam calculations. |

OUT+IN | y | (Vector) | The measurement vector. |

GIN | f0 | (Numeric, Default: -1) | User input for F0 [see description for default] |

GIN | df | (Numeric, Default: -1) | User input for DF [see description for default] |