Test with PE; parameters from Abe, Jernigan & Flory JCP 1969
1,30                                     number of bonds/unit, number of "loops"
3,3,       1.53,0.,0.                    row, cols of U-matrix of bond i, vector
1.,    0.54,   0.54                      U-matrix for bond i, row by row
0.54,  0.54,   0.048                     .
0.54,  0.048,  0.54                      .                    last row
180.,  +60.,   -60.                      PHI's for the states of bond i
112.,    0.,     0.                      THETA's of the states of bond i