compute the melting temperature of nucleic acid duplex

 This program computes, for a nucleic acid duplex, the enthalpy, the
 entropy and the melting temperature of the helix-coil
 transitions. Three types of hybridisation are possible: DNA/DNA,
 DNA/RNA, and RNA/RNA. The program first computes the hybridisation
 enthalpy and entropy from the elementary parameters of each Crick's
 pair by the nearest-neighbor method. Then the melting temperature is
 computed. The set of thermodynamic parameters can be easily changed,
 for instance following an experimental breakthrough.