3.17 Torsion angle analysis

Examples:

$ rna_torsions.py ./input/4GXY_min.pdb
f, alphaprime, beta
input ./input/4GXY_min.pdb <Residue G het=  resseq=2 icode= >, -64.20924484900823, -143.18546007904766
input ./input/4GXY_min.pdb <Residue C het=  resseq=3 icode= >, 2.3394112025736815, 70.4052871669199

Comparison:

$ rna_x3dna.py input/4GXY_min.pdb -s
input: input/4GXY_min.pdb
   nt id   res  alpha   beta  gamma  delta  epsilon  zeta      e-z           chi     phase-angle sugar-type  ssZp    Dp  splay     paired
0   1  G  A.G2    NaN -143.2  153.7   82.5    -92.3 -31.9  -60(..)  -179.0(anti)  19.5(C3'-endo)  ~C3'-endo  4.39  4.56  18.32  no paired
1   2  C  A.C3 -111.4   70.4  160.0   80.6      NaN   NaN      NaN  -177.6(anti)  11.1(C3'-endo)  ~C3'-endo   NaN   NaN    NaN  no paired