Program for prediction dihedral angle from vicinal coupling constant with 3-sphere approach

3-Sphere approach is applied on prediction dihedral angle θHnHn+1deg only from vicinal coupling constant 3JHnHn+1Hz with Java script, in comparation with angles calculated from the differences between two atoms of carbon chemical shift (ΔδCnCn+1ppm) and Karplus equations. The trigonometric equations 1, 2 ensuring the right sign along the D-, L series rule.