2020_06_09 F2charm FFNS4 uonly

• F2charm in FFNS for low Q2 is non zero for uonly-PDF

F2charm with theory=99 using uonly
      x        Q2     APFEL  yadism  yadism_error  rel_err[%]
0  0.01  2.000000  0.000260     0.0           0.0      -100.0
1  0.01  2.444444  0.000304     0.0           0.0      -100.0
2  0.01  2.888889  0.000336     0.0           0.0      -100.0
3  0.01  3.333333  0.000356     0.0           0.0      -100.0
4  0.01  3.777778  0.000366     0.0           0.0      -100.0
5  0.01  4.222222  0.000000     0.0           0.0         NaN
6  0.01  4.666667  0.000000     0.0           0.0         NaN
7  0.01  5.111111  0.000000     0.0           0.0         NaN
8  0.01  5.555556  0.000000     0.0           0.0         NaN
9  0.01  6.000000  0.000000     0.0           0.0         NaN

Theory 99:

{'ID': 22,
 'PTO': 0,
 'FNS': 'FFNS',
 'DAMP': 0,
 'IC': 0,
 'ModEv': 'EXA',
 'XIR': 1.0,
 'XIF': 1.0,
 'NfFF': 4,
 'MaxNfAs': 6,
 'MaxNfPdf': 6,
 'Q0': 1,
 'alphas': 0.11800000000000001,
 'Qref': 91.2,
 'QED': 0,
 'alphaqed': 0.007496251999999999,
 'Qedref': 1.777,
 'SxRes': 0,
 'SxOrd': 'LL',
 'HQ': 'POLE',
 'mc': 2,
 'Qmc': 2,
 'kcThr': 1.0,
 'mb': 4,
 'Qmb': 4,
 'kbThr': 1.0,
 'mt': 173.07,
 'Qmt': 173.07,
 'ktThr': 1.0,
 'CKM': '0.97428 0.22530 0.003470 0.22520 0.97345 0.041000 0.00862 0.04030 0.999152',
 'MZ': 91.1876,
 'MW': 80.398,
 'GF': 1.1663787e-05,
 'SIN2TW': 0.23126,
 'TMC': 0,
 'MP': 0.938,
 'Comments': 'LO baseline for small-x res',
 'global_nx': 0,
 'EScaleVar': 1,
 '_modify_time': '2020-05-28 16:55:02.164765'}

might be related to https://github.com/scarrazza/apfel/issues/22