cst_cnv_trg_mk.nco

// Linear  interpolation of zenith angle
// usage ncap2 -v -O -s 'zd=30.0; exp=25; trg=95; -S hyperspectral_zn.nco cst_cnv_trg_zn_exp_trg.nc cst_cnv_trg.nc

// remember min_cords returns -1 if out of bounds


  // linear search for nearest grud point
  //  assume that zenith is NOT sorted
  // convert from degrees to cos(zn);
  zd=cos( zd*3.14159265359/180.0);

  *min=999.0;
  *t_sz=$time2.size;
  *min_idx=0;
  for(*idx=0 ; idx<t_sz; idx++) 
    if( fabs(zenith(idx)-zd) <min)
    {    
        min=fabs(zenith(idx)-zd);
        min_idx=idx;    
    }
  
  zi=min_idx;
  
 


  // remeber min_cords returns -1 if out of bounds
  *trgi=min_coords(target,trg);
  // out of bounds
  if( trgi==-1 ) 
  {
    // to little
    if( trg< target(0) ) 
      trgi=0;   
    // too much
   else
      trgi=$target.size-1;

    print("trgi out of bounds(target) using the value ");
    print(target(trgi),"%d\n");    
  }


  // assume the following values - 0/25, 1/30, 2/35, 3/45
  // remeber min_cords returns -1 if out of bounds
  *expri=min_coords(exposure, expr);  
  if( expri==-1)
  {  
    if(expr< exposure(0))
       expri=0;
    else
      expri=$exposure.size-1;

    print("expri out of bounds(target) using the value ");
    print(exposure(expri),"%d\n");    

  }

  cst_cnv_trg_nw = cst_cnv_trg(zi,expri,trgi,:).float();