Basics

##
Basics

A table being a particular type of the GDF format, all the SIC and GREG commands can be used on tables. Here is a typical example:

           1 transpose 12cs21.uvt 12cs21.tuv 21
           2 column x 1 y 2 /table 12cs21.tuv
           3 limits
           4 box
           5 points
           6 define image tuv 12cs21.tuv read
           7 limits /var tuv[1] tuv[2]
           8 box
           9 points uv[1] uv[2]
          10 define double mjd /like tuv[1]
          11 let mjd tuv[4]+tuv[5]/24.
          12 delete /var tuv
          13 define image tuv 12cs21.tuv write
          14 for ichan 1 to (tuv%dim[2]-7)/3
          15    let tuv['7+3*ichan'] -tuv['7+3*ichan'] /where tuv['5+3*ichan',].ge.100.0
          16 next ichan
          17 delete /var tuv

Comments:

Step 1
  Transposes columns and lines of the table. Indeed, CLIC naturally produces the tables in visibility order, which is not well suited for display where it is more useful to have all information about a visibility in a line than in a column. By convention, the extension of transposed tables is tuv.
Steps 2-5
  Read and plot the and coordinate to give an idea of the coverage of the data inside the table.
Steps 6-12
  Steps 6 to 9 gives the same result as steps 2 to 5 except than here all the table is red and stored in the sic tuv variable. This enables computation of complex quantities from several table column, e.g. the computation of a continuous variable of time (mjd) in steps 10 and 11.
Steps 13-17
  Change the sign of the weight columns for all visibilities whose real amplitude is greater or equal to 100.0. Changing the sign of the weight is a reversible way to flag out a visibility. Indeed, it is always possible to change again the sign. This operation is done in place, i.e. the input file is overwritten in step 17 as announced by the write option of command define in step 13.