hyperspectral_zn_xps_img_wht.nco

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


// remember min_cords returns -1 if out of bounds
if( zd< zenith(0)) 
  zd=zenith(0);  
else if( zd> zenith(-1) )
  zd=zenith(-1);
*zi=min_coords(zenith,zd);

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

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

// remeber min_cords returns -1 if out of bounds
*trgi=min_coords(target,trg);
// out of bounds
if( trgi==-1 ) {
  // to little
  if( exp< 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");    
}




*za=0;
*zb=1;


if ( zi==0 )
{ 
  za=0;
  zb=1;
}
 else if ( zi== $zenith.size-1 )
 {
 za=zi-1;
 zb=zi;
 }
 else if(  zd >= zenith(zi)  )
{
  za=zi;
  zb=zi+1;
}
 else 
{ 
 za=zi-1;
 zb=zi;
}


// get simple linear interpolation factor
*mfactor= (zd-zenith(za)) / ( zenith(zb) -zenith(za)).float();  
*xps_img_nw[wavelength]=0.0f;
xps_img_nw= (1.0f-mfactor) * xps_img_wht(za,expi,trgi,:)   + mfactor* xps_img_wht(zb,expi,trgi,:);  


{ xps_img_wht=xps_img_nw.ushort();}