`ECH_WAVECEN`

Determine the central wavelength of the order

Use a binary chop search to determine the order which corresponds to the given echelle gamma angle. Having determined the order, perform a similar search to determine the wavelength within the order which corresponds to the given echelle theta angle.

`ECH_INIT`

must be called before calling this routine.

`CALL`

`ECH_WAVECEN`

(`THETA`

, `GAMMA`

, `WC`

, `MC`

, `STATUS`

)

`READ` | `THETA` | `REAL` | Echelle theta angle corresponding to the current configuration (radians) |

`READ` | `GAMMA` | `REAL` | Echelle gamma angle corresponding to the current configuration (radians) |

`WRITE` | `WC` | `REAL` | Central wavelength corresponding to the current configuration (ie that wavelength which lies within order M and is closest to that in the centre of the field) |

`WRITE` | `MC` | `INTEGER` | Order number corresponding to the current configuration (the order closest to that in the centre of the field) |

`READ` , `WRITE` | `STATUS` | `INTEGER` | Global status value |

C.J. Hirst `UCL`

(`ZUVAD`

::`CJH`

)