& dcostheta(j,1,i)
dtauangle(j,1,2,i)=-1/sing*dcostau(j,1,2,i)
dcostau(j,1,3,i)=fac2*dcostheta(j,2,i)+fac4*
& dcostheta(j,2,i)-fac0*(-dc_norm(j,i-2+nres)-scalp*
& dc_norm(j,i-1))/vbld(i)
dtauangle(j,1,3,i)=-1/sing*dcostau(j,1,3,i)
& dcostheta(j,1,i)
dtauangle(j,1,2,i)=-1/sing*dcostau(j,1,2,i)
dcostau(j,1,3,i)=fac2*dcostheta(j,2,i)+fac4*
& dcostheta(j,2,i)-fac0*(-dc_norm(j,i-2+nres)-scalp*
& dc_norm(j,i-1))/vbld(i)
dtauangle(j,1,3,i)=-1/sing*dcostau(j,1,3,i)