+ do i=ithet_start,ithet_end
+c
+c do i=1,nfrag_back
+c ii = ifrag_back(2,i,iset)-ifrag_back(1,i,iset)
+c
+c Deviation of theta angles wrt constr_homology ref structures
+c
+ utheta_i=0.0d0 ! argument of Gaussian for single k
+ gutheta_i=0.0d0 ! Sum of Gaussians over constr_homology ref structures
+c do j=ifrag_back(1,i,iset)+2,ifrag_back(2,i,iset) ! original loop
+c over residues in a fragment
+c write (iout,*) "theta(",i,")=",theta(i)
+ do k=1,constr_homology
+c
+c dtheta_i=theta(j)-thetaref(j,iref)
+c dtheta_i=thetaref(k,i)-theta(i) ! original form without indexing
+ theta_diff(k)=thetatpl(k,i)-theta(i)
+c
+ utheta_i=-0.5d0*theta_diff(k)**2*sigma_theta(k,i) ! waga_theta rmvd from Gaussian argument
+c utheta_i=-0.5d0*waga_theta*theta_diff(k)**2*sigma_theta(k,i) ! waga_theta?
+ gtheta(k)=dexp(utheta_i) ! + min_utheta_i?
+ gutheta_i=gutheta_i+dexp(utheta_i) ! Sum of Gaussians (pk)
+c Gradient for single Gaussian restraint in subr Econstr_back
+c dutheta(j-2)=dutheta(j-2)+wfrag_back(1,i,iset)*dtheta_i/(ii-1)
+c
+ enddo
+c write (iout,*) "gtheta",(gtheta(k),k=1,constr_homology) ! exps
+c write (iout,*) "i",i," gutheta_i",gutheta_i ! sum of exps
+
+c
+c Gradient for multiple Gaussian restraint
+ sum_gtheta=gutheta_i
+ sum_sgtheta=0.0d0
+ do k=1,constr_homology
+c New generalized expr for multiple Gaussian from Econstr_back
+ sgtheta=-gtheta(k)*theta_diff(k)*sigma_theta(k,i) ! waga_theta rmvd
+c
+c sgtheta=-gtheta(k)*theta_diff(k)*sigma_theta(k,i)*waga_theta ! right functional form?
+ sum_sgtheta=sum_sgtheta+sgtheta ! cum variable
+ enddo
+c Final value of gradient using same var as in Econstr_back
+ gloc(nphi+i-2,icg)=gloc(nphi+i-2,icg)
+ & +sum_sgtheta/sum_gtheta*waga_theta
+ & *waga_homology(iset)
+c dutheta(i-2)=sum_sgtheta/sum_gtheta*waga_theta
+c & *waga_homology(iset)
+c dutheta(i)=sum_sgtheta/sum_gtheta
+c
+c Uconst_back=Uconst_back+waga_theta*utheta(i) ! waga_theta added as weight
+ Eval=Eval-dLOG(gutheta_i/constr_homology)
+c write (iout,*) "utheta(",i,")=",utheta(i) ! -ln of sum of exps
+c write (iout,*) "Uconst_back",Uconst_back ! sum of -ln-s
+c Uconst_back=Uconst_back+utheta(i)
+ enddo ! (i-loop for theta)
+#ifdef DEBUG
+ write(iout,*) "------- theta restrs end -------"
+#endif
+ endif
+c
+c Deviation of local SC geometry
+c
+c Separation of two i-loops (instructed by AL - 11/3/2014)
+c
+c write (iout,*) "loc_start =",loc_start,"loc_end =",loc_end
+c write (iout,*) "waga_d",waga_d
+
+#ifdef DEBUG
+ write(iout,*) "------- SC restrs start -------"
+ write (iout,*) "Initial duscdiff,duscdiffx"
+ do i=loc_start,loc_end
+ write (iout,*) i,(duscdiff(jik,i),jik=1,3),
+ & (duscdiffx(jik,i),jik=1,3)
+ enddo
+#endif
+ do i=loc_start,loc_end
+ usc_diff_i=0.0d0 ! argument of Gaussian for single k
+ guscdiff(i)=0.0d0 ! Sum of Gaussians over constr_homology ref structures
+c do j=ifrag_back(1,i,iset)+1,ifrag_back(2,i,iset)-1 ! Econstr_back legacy
+c write(iout,*) "xxtab, yytab, zztab"
+c write(iout,'(i5,3f8.2)') i,xxtab(i),yytab(i),zztab(i)
+ do k=1,constr_homology
+c
+ dxx=-xxtpl(k,i)+xxtab(i) ! Diff b/w x component of ith SC vector in model and kth ref str?
+c Original sign inverted for calc of gradients (s. Econstr_back)
+ dyy=-yytpl(k,i)+yytab(i) ! ibid y
+ dzz=-zztpl(k,i)+zztab(i) ! ibid z
+c write(iout,*) "dxx, dyy, dzz"
+c write(iout,'(2i5,3f8.2)') k,i,dxx,dyy,dzz
+c
+ usc_diff_i=-0.5d0*(dxx**2+dyy**2+dzz**2)*sigma_d(k,i) ! waga_d rmvd from Gaussian argument
+c usc_diff(i)=-0.5d0*waga_d*(dxx**2+dyy**2+dzz**2)*sigma_d(k,i) ! waga_d?
+c uscdiffk(k)=usc_diff(i)
+ guscdiff2(k)=dexp(usc_diff_i) ! without min_scdiff
+ guscdiff(i)=guscdiff(i)+dexp(usc_diff_i) !Sum of Gaussians (pk)
+c write (iout,'(i5,6f10.5)') j,xxtab(j),yytab(j),zztab(j),
+c & xxref(j),yyref(j),zzref(j)
+ enddo
+c
+c Gradient
+c
+c Generalized expression for multiple Gaussian acc to that for a single
+c Gaussian in Econstr_back as instructed by AL (FP - 03/11/2014)
+c
+c Original implementation
+c sum_guscdiff=guscdiff(i)
+c
+c sum_sguscdiff=0.0d0
+c do k=1,constr_homology
+c sguscdiff=-guscdiff2(k)*dscdiff(k)*sigma_d(k,i)*waga_d !waga_d?
+c sguscdiff=-guscdiff3(k)*dscdiff(k)*sigma_d(k,i)*waga_d ! w min_uscdiff
+c sum_sguscdiff=sum_sguscdiff+sguscdiff
+c enddo
+c
+c Implementation of new expressions for gradient (Jan. 2015)
+c
+c grad_uscdiff=sum_sguscdiff/(sum_guscdiff*dtab) !?
+ do k=1,constr_homology
+c
+c New calculation of dxx, dyy, and dzz corrected by AL (07/11), was missing and wrong
+c before. Now the drivatives should be correct
+c
+ dxx=-xxtpl(k,i)+xxtab(i) ! Diff b/w x component of ith SC vector in model and kth ref str?
+c Original sign inverted for calc of gradients (s. Econstr_back)
+ dyy=-yytpl(k,i)+yytab(i) ! ibid y
+ dzz=-zztpl(k,i)+zztab(i) ! ibid z
+c
+c New implementation
+c
+ sum_guscdiff=guscdiff2(k)*!(dsqrt(dxx*dxx+dyy*dyy+dzz*dzz))* -> wrong!
+ & sigma_d(k,i) ! for the grad wrt r'
+c sum_sguscdiff=sum_sguscdiff+sum_guscdiff
+c
+c
+c New implementation
+ sum_guscdiff = waga_homology(iset)*waga_d*sum_guscdiff
+ do jik=1,3
+ duscdiff(jik,i-1)=duscdiff(jik,i-1)+
+ & sum_guscdiff*(dXX_C1tab(jik,i)*dxx+
+ & dYY_C1tab(jik,i)*dyy+dZZ_C1tab(jik,i)*dzz)/guscdiff(i)
+ duscdiff(jik,i)=duscdiff(jik,i)+
+ & sum_guscdiff*(dXX_Ctab(jik,i)*dxx+
+ & dYY_Ctab(jik,i)*dyy+dZZ_Ctab(jik,i)*dzz)/guscdiff(i)
+ duscdiffx(jik,i)=duscdiffx(jik,i)+
+ & sum_guscdiff*(dXX_XYZtab(jik,i)*dxx+
+ & dYY_XYZtab(jik,i)*dyy+dZZ_XYZtab(jik,i)*dzz)/guscdiff(i)
+c
+#ifdef DEBUG
+ write(iout,*) "jik",jik,"i",i
+ write(iout,*) "dxx, dyy, dzz"
+ write(iout,'(2i5,3f8.2)') k,i,dxx,dyy,dzz
+ write(iout,*) "guscdiff2(",k,")",guscdiff2(k)
+c write(iout,*) "sum_sguscdiff",sum_sguscdiff
+cc write(iout,*) "dXX_Ctab(",jik,i,")",dXX_Ctab(jik,i)
+c write(iout,*) "dYY_Ctab(",jik,i,")",dYY_Ctab(jik,i)
+c write(iout,*) "dZZ_Ctab(",jik,i,")",dZZ_Ctab(jik,i)
+c write(iout,*) "dXX_C1tab(",jik,i,")",dXX_C1tab(jik,i)
+c write(iout,*) "dYY_C1tab(",jik,i,")",dYY_C1tab(jik,i)
+c write(iout,*) "dZZ_C1tab(",jik,i,")",dZZ_C1tab(jik,i)
+c write(iout,*) "dXX_XYZtab(",jik,i,")",dXX_XYZtab(jik,i)
+c write(iout,*) "dYY_XYZtab(",jik,i,")",dYY_XYZtab(jik,i)
+c write(iout,*) "dZZ_XYZtab(",jik,i,")",dZZ_XYZtab(jik,i)
+c write(iout,*) "duscdiff(",jik,i-1,")",duscdiff(jik,i-1)
+c write(iout,*) "duscdiff(",jik,i,")",duscdiff(jik,i)
+c write(iout,*) "duscdiffx(",jik,i,")",duscdiffx(jik,i)
+c endif
+#endif
+ enddo
+ enddo
+c
+c uscdiff(i)=-dLOG(guscdiff(i)/(ii-1)) ! Weighting by (ii-1) required?
+c usc_diff(i)=-dLOG(guscdiff(i)/constr_homology) ! + min_uscdiff ?
+c
+c write (iout,*) i," uscdiff",uscdiff(i)
+c
+c Put together deviations from local geometry
+
+c Uconst_back=Uconst_back+wfrag_back(1,i,iset)*utheta(i)+
+c & wfrag_back(3,i,iset)*uscdiff(i)
+ Erot=Erot-dLOG(guscdiff(i)/constr_homology)
+c write (iout,*) "usc_diff(",i,")=",usc_diff(i) ! -ln of sum of exps
+c write (iout,*) "Uconst_back",Uconst_back ! cum sum of -ln-s
+c Uconst_back=Uconst_back+usc_diff(i)
+c
+c Gradient of multiple Gaussian restraint (FP - 04/11/2014 - right?)
+c
+c New implment: multiplied by sum_sguscdiff
+c
+
+ enddo ! (i-loop for dscdiff)
+
+c endif
+
+#ifdef DEBUG
+ write(iout,*) "------- SC restrs end -------"
+ write (iout,*) "------ After SC loop in e_modeller ------"
+ do i=loc_start,loc_end
+ write (iout,*) "i",i," gradc",(gradc(j,i,icg),j=1,3)
+ write (iout,*) "i",i," gradx",(gradx(j,i,icg),j=1,3)
+ enddo
+ if (waga_theta.eq.1.0d0) then
+ write (iout,*) "in e_modeller after SC restr end: dutheta"
+ do i=ithet_start,ithet_end
+ write (iout,*) i,dutheta(i)
+ enddo
+ endif
+ if (waga_d.eq.1.0d0) then
+ write (iout,*) "e_modeller after SC loop: duscdiff/x"
+ do i=1,nres
+ write (iout,*) i,(duscdiff(j,i),j=1,3)
+ write (iout,*) i,(duscdiffx(j,i),j=1,3)
+ enddo
+ endif
+#endif