MDI_ROLL(3)



NAME

     mdi_roll -- MDI roll angle in degrees


SYNOPSIS

     #include <soi_time.h>
     #include <soi_ephem.h>
     #include <soi_sds.h>

     int mdi_roll (char *rolltable, TIME tobs, double *roll, TIME *tmod)


DESCRIPTION

     mdi_roll() interpolates the tabulated MDI roll angles stored
     in  file  rolltable  to the requested observation time tobs.
     The interpolated roll angle in degrees and the last  modifi-
     cation  time  of  the  table  are returned in roll and tmod,
     respectively.



FILES

     ~CM/tables/ephemeris/mdi_roll.raw
     ~CM/tables/ephemeris/mdi_roll.smooth
     ~CM/lib/_($MACH)/libastro.a


DIAGNOSTICS

     Return values:
     0                         normal return
     MDIROLL_CANT_READ_TABLE   can't read table
     MDIROLL_BAD_TABLE         entries in table not time ordered
     MDIROLL_CANT_INTERPOLATE  requested time out of table range

     Except in the case of normal return, roll and tmod  are  set
     to MISSING.


BUGS

     Does not extrapolate.

     Always linearly interpolates.

     Roll table is read on first call and cannot  be  changed  on
     subsequent calls.


AUTHOR

     Keh-Cheng Chu


HISTORY

     1999-01-13      SOI Version 2.1