TString dir = gROOT->GetTutorialDir();
TFITSHDU* hdu = new TFITSHDU(dir + "/fitsio/rmf.fits", 1);
int rownum = 214; // FITS tables are indexed starting from 1
TString colname1 = "F_CHAN";
TString colname2 = "N_CHAN";
TString colname3 = "MATRIX";

printf("reading in row %d, column %s \n", rownum+1, colname1.Data());
TArrayD *arr1 = hdu->GetTabVarLengthVectorCell(rownum, colname1);
printf("(%f, %f) \n", arr1->At(0), arr1->At(1));

printf("reading in row %d, column %s \n", rownum+1, colname2.Data());
TArrayD *arr2 = hdu->GetTabVarLengthVectorCell(rownum, colname2);
printf("(%f, %f) \n", arr2->At(0), arr2->At(1));

printf("reading in row %d, column %s \n", rownum+1, colname3.Data());
TArrayD *arr3 = hdu->GetTabVarLengthVectorCell(rownum, colname3);
printf("(%e, %e, %e, %e, %e, ...) \n", arr3->At(0), arr3->At(1), arr3->At(2), arr3->At(3), arr3->At(4));

gROOT->GetListOfCanvases()->Draw()