// bdna() - create average B-form duplex
molecule bdna( string seq )
{
	molecule m;
	string cseq;

	cseq = wc_complement( seq, "", "dna" );
	m = wc_helix( seq, "", "dna", cseq, "", "dna",
		2.25, -4.96, 36.0, 3.38, "s5a5s3a3");
	return( m );
};