/*     CalculiX - A 3-dimensional finite element program                 */
/*              Copyright (C) 1998-2021 Guido Dhondt                          */

/*     This program is free software; you can redistribute it and/or     */
/*     modify it under the terms of the GNU General Public License as    */
/*     published by the Free Software Foundation(version 2);    */
/*                    */

/*     This program is distributed in the hope that it will be useful,   */
/*     but WITHOUT ANY WARRANTY; without even the implied warranty of    */ 
/*     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the      */
/*     GNU General Public License for more details.                      */

/*     You should have received a copy of the GNU General Public License */
/*     along with this program; if not, write to the Free Software       */
/*     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.         */

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include "CalculiX.h"
#ifdef SPOOLES 
   #include "spooles.h"
#endif
#ifdef SGI
   #include "sgi.h"
#endif
#ifdef TAUCS
   #include "tau.h"
#endif

#define max(a,b) ((a) >= (b) ? (a) : (b))

void checkconvergence(double *co, ITG *nk, ITG *kon, ITG *ipkon, char *lakon,
	  ITG *ne, double *stn, ITG *nmethod, 
	  ITG *kode, char *filab, double *een, double *t1act,
          double *time, double *epn,ITG *ielmat,char *matname,
          double *enern, double *xstaten, ITG *nstate_, ITG *istep,
          ITG *iinc, ITG *iperturb, double *ener, ITG *mi, char *output,
          ITG *ithermal, double *qfn, ITG *mode, ITG *noddiam, double *trab,
          ITG *inotr, ITG *ntrans, double *orab, ITG *ielorien, ITG *norien,
          char *description,double *sti,
	  ITG *icutb, ITG *iit, double *dtime, double *qa, double *vold,
          double *qam, double *ram1, double *ram2, double *ram,
          double *cam, double *uam, ITG *ntg, double *ttime,
          ITG *icntrl, double *theta, double *dtheta, double *veold,
          double *vini, ITG *idrct, double *tper,ITG *istab, double *tmax, 
          ITG *nactdof, double *b, double *tmin, double *ctrl, double *amta,
          ITG *namta, ITG *itpamp, ITG *inext, double *dthetaref, ITG *itp,
          ITG *jprint, ITG *jout, ITG *uncoupled, double *t1, ITG *iitterm,
          ITG *nelemload, ITG *nload, ITG *nodeboun, ITG *nboun, ITG *itg,
          ITG *ndirboun, double *deltmx, ITG *iflagact,char *set,ITG *nset,
	  ITG *istartset,ITG *iendset,ITG *ialset, double *emn, double *thicke,
	  char *jobnamec,ITG *mortar,ITG *nmat,ITG *ielprop,double *prop,
	  ITG *ialeatoric,ITG *kscale,
	  double *energy, double *allwk, double *energyref, double *emax,
	  double *r_abs, double *enetoll, double *energyini, double *allwkini,
	  double *temax, double *sizemaxinc, ITG* ne0, ITG* neini,
	  double *dampwk, double *dampwkini, double *energystartstep) {

    ITG i0,ir,ip,ic,il,ig,ia,iest,iest1=0,iest2=0,iconvergence,idivergence,
	ngraph=1,k,*ipneigh=NULL,*neigh=NULL,*inum=NULL,id,istart,iend,inew,
        i,j,mt=mi[1]+1,iexceed,iforceincsize=0,kscalemax,itf2f;

    double df,dc,db,dd,ran,can,rap,ea,cae,ral,da,*vr=NULL,*vi=NULL,*stnr=NULL,
	*stni=NULL,*vmax=NULL,*stnmax=NULL,*cs=NULL,c1[2],c2[2],reftime,
        *fn=NULL,*eenmax=NULL,*fnr=NULL,*fni=NULL,*qfx=NULL,*cdn=NULL,
        *cdnr=NULL,*cdni=NULL,tmp, maxdecay=0.0, r_rel,cetol;

    /* reset ialeatoric to zero */

    *ialeatoric=0;

    /* next lines are active if the number of contact elements was
       changed in the present increment */

    if ((*iflagact==1)&&(*mortar!=1)){
	if(ctrl[0]<*iit+4)ctrl[0]=*iit+4;
	if(ctrl[1]<*iit+8)ctrl[1]=*iit+8;
	ctrl[3]+=1;
    }
	
    i0=ctrl[0];ir=ctrl[1];ip=ctrl[2];ic=ctrl[3];il=ctrl[4];ig=ctrl[5];
    ia=ctrl[7];df=ctrl[10];dc=ctrl[11];db=ctrl[12];da=ctrl[13];dd=ctrl[16];
    ran=ctrl[18];can=ctrl[19];rap=ctrl[22];ea=ctrl[23];cae=ctrl[24];
    ral=ctrl[25];cetol=ctrl[39];kscalemax=ctrl[55];itf2f=ctrl[56];

    /* for face-to-face penalty contact: increase the number of iterations
       in two subsequent increments in order to increase the increment size */

    if(*mortar==1){ig+=12;il+=12;}

    /* if iconvergence=0 the increment did not yet converge, iterations are
                         continued
       if idivergence=1 the increment diverged and has to be reiterated
                        with a smaller size */

    idivergence=0;

    /* check for forced divergence (due to divergence of a user material
       routine */

    if(qa[2]>0.){idivergence=1;}

    if(*ithermal!=2){
	if(qa[0]>ea*qam[0]){
	    if(*iit<=ip){c1[0]=ran;}
	    else{c1[0]=rap;}
	    c2[0]=can;
	}
	else{
	    c1[0]=ea;
	    c2[0]=cae;
	}
	if(ram1[0]<ram2[0]){ram2[0]=ram1[0];}
    }
    if(*ithermal>1){
	if(qa[1]>ea*qam[1]){
	    if(*iit<=ip){c1[1]=ran;}
	    else{c1[1]=rap;}
	    c2[1]=can;
	}
	else{
	    c1[1]=ea;
	    c2[1]=cae;
	}
	if(ram1[1]<ram2[1]){ram2[1]=ram1[1];}
    }

    iconvergence=0; 
 
    /* mechanical */

    if(*ithermal<2){
//         number of iterations exceeding 1
	if((*iit>1)&&
//         force residual criterion satisfied (0.5 %)
           (ram[0]<=c1[0]*qam[0])&&
//         no significant change in contact elements
           (*iflagact==0)&&
//         cetol criterion satisfied if *visco
           ((*nmethod!=-1)||(qa[3]<=cetol))&&
//         solution change criterion satisfied (1 %)
	   ((cam[0]<=c2[0]*uam[0])||
	    (((ram[0]*cam[0]<c2[0]*uam[0]*ram2[0])||(ram[0]<=ral*qam[0])||
	      (qa[0]<=ea*qam[0]))&&(*ntg==0))||
	    (cam[0]<1.e-8))) iconvergence=1;
    }

    /* thermal */

    if(*ithermal==2){
	if((ram[1]<=c1[1]*qam[1])&&
           (cam[2]<*deltmx)&&
	   ((cam[1]<=c2[1]*uam[1])||
//   change 25.11.2017
//	    (((ram[1]*cam[1]<c2[1]*uam[1]*ram2[1])||(ram[1]<=ral*qam[1])||
	    (((ram[1]*cam[1]<c2[1]*uam[1]*ram2[1])||((ram[1]<=ral*qam[1])&&(*iit>1))||
	      (qa[1]<=ea*qam[1]))&&(*ntg==0))||
	    (cam[1]<1.e-8)))iconvergence=1;
    }

    /* thermomechanical */

    if(*ithermal==3){
	if(((*iit>1)&&(ram[0]<=c1[0]*qam[0])&&
            ((*nmethod!=-1)||(qa[3]<=cetol))&&
	    ((cam[0]<=c2[0]*uam[0])||
	     (((ram[0]*cam[0]<c2[0]*uam[0]*ram2[0])||(ram[0]<=ral*qam[0])||
	       (qa[0]<=ea*qam[0]))&&(*ntg==0))||
	     (cam[0]<1.e-8)))&&
	   ((ram[1]<=c1[1]*qam[1])&&
            (cam[2]<*deltmx)&&
	    ((cam[1]<=c2[1]*uam[1])||
	     (((ram[1]*cam[1]<c2[1]*uam[1]*ram2[1])||(ram[1]<=ral*qam[1])||
	       (qa[1]<=ea*qam[1]))&&(*ntg==0))||
	     (cam[1]<1.e-8))))iconvergence=1;
    }

    /* reset kscale */

    if(iconvergence==1){
	if(*kscale>1){
	    *kscale=1;
	    iconvergence=0;
	    printf("\n restoring the elastic contact stifnesses to their original values \n\n");
	}
    }

// # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # 
//    MPADD start
    /* 
         Energy conservation convergence: only for implicit dynamic calculations 
	(convergence is not checked in explicit dynamics)

         Main variables and meaning
         
         r_rel     : modified energy conservation criterion
         emax      : maximum value of the energy over the time history
         r     : energy residual (Eint + K + Econt - Wext - Wdamp -Eref)
         enetoll   : energy conservation tolerance
         tmp       : auxiliary temporary variable
         maxdecay  : \hat(r)^{max}(\theta) -> value of the decay boundary 
                       for r_hat. 
         
         Proposed by Matteo Pacher */

    if((*nmethod==4)&&(*ithermal<2)&&(*uncoupled==0)&&(iconvergence==1)&&(*ne==*ne0)&&(*neini==*ne0)&&(*idrct==0)) {
    
	/* Update the value of the maximum energy of the system emax
	   (contact energy is not taken into account because small) */

	*emax=max(*emax,fabs(energy[0]-energystartstep[0]));
	*emax=max(*emax,fabs(energy[1]));
	*emax=max(*emax,fabs(*allwk));
	
	// energy residual (only calculated in the absence of contact); 
        // if <=0: loss of energy 

	*r_abs=energy[0]+energy[1]+energy[2]+energy[3]-*energyref-*allwk-*dampwk;
	
	// Absolute tolerance check (when the error is really small --> beginning of simulation)

	if(fabs(*r_abs)>=*enetoll/4) {

	    // Normal strategy: Relative error
	    
	    /* Compute admissible decay*/

	    maxdecay=*enetoll/2*(1+sqrt(*theta));
	    
	    /* modified r_hat criterion */

	    r_rel=*r_abs/(*emax);
	    if(r_rel<=-maxdecay) {
	      // deactivated on 22.03.2019
	      // energy/work may not be calculated correctly for forced BC
	      // (example: shaft)
	      // following line deactiveted on 16.07.2021
	      //      		idivergence=1;
	    }else{
		
		/* Check if the residual is too close to the boundary */

		if(r_rel<=-0.9*maxdecay) {
		    *istab=0; // keep the increment size
		}
	    }
	}
    }
    
    /* Contact Strategy: limit jumps and time increment during contact based
       on the natural frequency of oscillation of contact elements 
       Implicit dynamic calculations only */

    if((*nmethod==4)&&(*ithermal<2)&&(*uncoupled==0)&&(iconvergence==1)&&((*ne!=*ne0)||(*neini!=*ne0))){

	/* store temporarly the value of emax: in case of forced divergence 
	   emax has to be reset. */

	tmp=*emax;
	
	/* Update the value of the maximum energy of the system emax
	  (contact energy is not taken into account because small) */

	*emax=max(*emax,fabs(energy[0]-energystartstep[0]));
	*emax=max(*emax,fabs(energy[1]));
	*emax=max(*emax,fabs(*allwk));
	
	/* maximum decay boundary */

	maxdecay=*enetoll/2*(1+sqrt(*theta));
	
	FORTRAN(checkimpacts,(ne,neini,temax,sizemaxinc,energyref,
			      tmin,tper,&idivergence,
			      &iforceincsize,istab,dtheta,r_abs,energy,energyini,
			      allwk,allwkini,dampwk,dampwkini,emax,mortar,
			      &maxdecay,enetoll));

	/* reset emax in case of forced divergence */

	if(idivergence==1){
	    *emax=tmp;
	}
	
	/* Adaption of the energy tolerance in case of violation due to 
	   contact jumps (rebounds). 
	   The user is aware of it via the output string. */

	if((*ne==*ne0)&&(*neini>*ne0)&&(idivergence==0)){
	    *r_abs=fabs(energy[0]+energy[1]+energy[2]+energy[3]-*energyref-*allwk-*dampwk);
	    tmp=1.3*(2.0*(*r_abs)/(*emax))/(1.0+sqrt(*theta));
	    *enetoll=max(*enetoll,tmp);
	    printf("\n Adaption of the max-decay boundary, enetoll = %f \n",*enetoll);
	}
	
	/*
	  Adaption of the energy residual during long periods of persistent contact.
	  Take care of the general (increasing) trend of the residual to avoid code stucks.
	*/

	if((iconvergence==1)&&(*ne<=*neini)){
	    tmp=energy[0]+energy[1]+energy[2]+energy[3]-*energyref-*allwk-*dampwk;
	    if(tmp>*r_abs){
		*r_abs=tmp;
		printf("\n Adaption of the energy residual in persistent contact, \n");
		printf("   an increasing trend has been detected.\n");
	    }
	}
    } else {
	*sizemaxinc=*tmax;
    }
//    MPADD end
// # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
    
    /* increment convergence reached */
	
    if((iconvergence==1)&&(idivergence==0)){

	FORTRAN(writesta,(istep,iinc,icutb,iit,ttime,time,dtime));
	if(*uncoupled){
	    if(*ithermal==2){
	        *iitterm=*iit;
		*ithermal=1;
		for(k=0;k<*nk;++k){t1[k]=vold[mt*k];}
		*iit=1;
		(ctrl[0])*=4;
		printf(" thermal convergence\n\n");
		*iflagact=0;
		return;
	    }else{
		*ithermal=3;
		*iit=*iitterm;
		(ctrl[0])/=4;
	    }
	}
	
	*icntrl=1;
	*icutb=0;
	*theta=*theta+*dtheta;
	
	/* defining a mean "velocity" for static calculations: is used to
	   extrapolate the present results for next increment */
	
	if(*nmethod != 4){
	    for(i=0;i<*nk;i++){
		for(j=1;j<mt;j++){
		    veold[mt*i+j]=(vold[mt*i+j]-vini[mt*i+j])/(*dtime);
		}
	    }
	}

        /* check whether size is to be set to a fixed value */

	if(iforceincsize==1){
	    *dtheta=*sizemaxinc;
	    *dthetaref=*sizemaxinc;
	    printf(" convergence; new increment size is forced to %e\n\n",*dtheta**tper);
	}
	
	/* check whether next increment size must be decreased */
	
	else if((*iit>il)&&(*idrct==0)){
	    if(*mortar==0){
		*dtheta=*dthetaref*db;
		*dthetaref=*dtheta;
		printf(" convergence; the increment size is decreased to %e\n\n",*dtheta**tper);
		if(*dtheta<*tmin){
		    printf("\n *ERROR: increment size smaller than minimum\n");
		    printf(" best solution and residuals are in the frd file\n\n");
		    NNEW(fn,double,mt**nk);
		    NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
		    FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,
                      nk,sti,stn,ipkon,inum,kon,lakon,ne,mi,orab,
		      ielorien,co,itg,ntg,vold,ielmat,thicke,ielprop,prop));
		    ++*kode;

		    (*ttime)+=(*time);
		    frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
			kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
                        xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
                        trab,inotr,ntrans,orab,ielorien,norien,description,
                        ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
                        &ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
                        ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,
                        cdn,mortar,cdnr,cdni,nmat,ielprop,prop,sti);

		    FORTRAN(stop,());
		}
	    }
	    else{
		printf("convergence\n\n");}
	}
	
	/* check whether next increment size can be increased */
	
	else if(*iit<=ig){
	    if((*istab==1)&&(*idrct==0)){
		*dtheta=*dthetaref*dd;
		*dthetaref=*dtheta;
		printf(" convergence; the increment size is increased to %e\n\n",*dtheta**tper);
	    }
	    else{
		*istab=1;
		printf(" convergence\n\n");
		*dtheta=*dthetaref;
	    }
	}
	else{
	    *istab=0;
	    printf(" convergence\n\n");
	    *dtheta=*dthetaref;
	}
	
	/* check whether new increment size exceeds maximum increment
           size allowed (by the user) */

	if((*dtheta>*sizemaxinc)&&(*idrct==0)){
	    *dtheta=*sizemaxinc;
	    *dthetaref=*dtheta;
	    printf(" the increment size exceeds the maximum allowed and is decreased to %e\n\n",*dtheta**tper);
	}

        /* check whether new time point exceeds end of step */

	if(*dtheta>=1.-*theta){
	    if(*dtheta>1.-*theta){iexceed=1;}else{iexceed=0;}
	    *dtheta=1.-*theta;
	    *dthetaref=*dtheta;
	    if(iexceed==1)
		printf(" the increment size exceeds the remainder of the step and is decreased to %e\n\n",*dtheta**tper);
	}

        /* check whether the end of the new increment exceeds a time point;
           if itp=1 the increment just finished ends at a time point */

	if((*itpamp>0)&&(*idrct==0)){
	    if(*itp==1){
		*jprint=*jout;
	    }else{
		*jprint=*jout+1;
	    }
	    if(namta[3**itpamp-1]<0){
		reftime=*ttime+*time+*dtheta**tper;
	    }else{
		reftime=*time+*dtheta**tper;
	    }
	    istart=namta[3**itpamp-3];
	    iend=namta[3**itpamp-2];
	    FORTRAN(identamta,(amta,&reftime,&istart,&iend,&id));
	    if(id<istart){
		inew=istart;
	    }else{
		inew=id+1;
	    }

            /* if the end of the new increment is less than a time
               point by less than 1.e-6 (theta-value) dtheta is
               enlarged up to this time point */

	    if((*inext==inew)&&(inew<=iend)){
		if(amta[2*inew-2]-reftime<1.e-6**tper){inew++;}
	    }

            /* inew: smallest time point exceeding time+dtheta*tper
               inext: smallest time point exceeding time */

	    if(*inext<inew){
		if(namta[3**itpamp-1]<0){
		    *dtheta=(amta[2**inext-2]-*ttime-*time)/(*tper);
		}else{
		    *dtheta=(amta[2**inext-2]-*time)/(*tper);
		}
		(*inext)++;
		*itp=1;
		printf(" the increment size exceeds a time point and is decreased to %e\n\n",*dtheta**tper);
	    }else{*itp=0;}
	}
    }
    else{

        /* no convergence */
	
	/* check for the amount of iterations */
	
	if(((*iit>ic)&&(*mortar==0))||((*mortar>1)&&(*iit>200))){
	    printf("\n *ERROR: too many iterations needed\n");
	    printf(" best solution and residuals are in the frd file\n\n");

	    FORTRAN(writestadiv,(istep,iinc,icutb,iit,ttime,time,dtime));

	    NNEW(fn,double,mt**nk);
	    NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
	    FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,nk,sti,stn,
		ipkon,inum,kon,lakon,ne,mi,orab,ielorien,co,itg,ntg,vold,
                ielmat,thicke,ielprop,prop));
	    ++*kode;

	    (*ttime)+=(*time);
	    frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
		kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
		xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
		trab,inotr,ntrans,orab,ielorien,norien,description,
		ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
		&ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
		ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,cdn,
		mortar,cdnr,cdni,nmat,ielprop,prop,sti);

	    FORTRAN(stop,());
	}	
	
	/* check for diverging residuals */

        /* if the user has not defined deltmx on the *HEAT
	 TRANSFER card it is set to a large value (1.e30,
	 cf. CalculiX.c); therefore, a comparison of cam[2]
	 with deltmx only makes sense for cam[2]<1.e30 */
      
	if((*iit>=i0)||(fabs(ram[0])>1.e20)||(fabs(cam[0])>1.e20)||
	               (fabs(ram[1])>1.e20)||(fabs(cam[1])>1.e20)||
	   ((cam[2]<1.e30)&&(cam[2]>*deltmx))||(idivergence==1)||
	               (iforceincsize==1)){
	    if((*ithermal!=2)&&(*mortar!=1)){
		if((ram1[0]>ram2[0])&&(ram[0]>ram2[0])&&(ram[0]>c1[0]*qam[0]))
		    idivergence=1;
	    }

	    if((*ithermal!=2)&&(*mortar==1)){

		if(ram[0]>1.e9){
		    printf("divergence allowed: residual force too large\n");
		    if((ram1[0]>ram2[0])&&(ram[0]>ram2[0])&&(ram[0]>c1[0]*qam[0]))
			idivergence=1;
		}

                /* number of contact elements does not change */

		if(*iflagact==0){
		    printf("divergence allowed: number of contact elements stabilized\n");
		    if((ram1[0]>ram2[0])&&(ram[0]>ram2[0])&&(ram[0]>c1[0]*qam[0])){
			if(cam[0]<=c2[0]*uam[0]){
			    *ialeatoric=1;
			}
		    }
		}
	    
                /* rate of number of contact elements is increasing */

		if(((ITG)ram[5]*(ITG)ram1[5]<0)&&((ITG)ram1[5]*(ITG)ram2[5]<0)){
		    
		    if(((ram[4]>0.98*ram1[4])&&(ram[4]<1.02*ram1[4]))&&
		       ((ram[4]>0.98*ram2[4])&&(ram[4]<1.02*ram2[4]))){
			printf("divergence allowed: repetitive pattern detected\n");
			if((ram1[0]>ram2[0])&&(ram[0]>ram2[0])&&(ram[0]>c1[0]*qam[0]))
			    idivergence=1;
		    }
		}
	    }

            /* check whether in a viscous step the allowable increase in viscous
               strain has been exceeded */

	    if((idivergence==0)&&((*nmethod==-1)&&(qa[3]>cetol))) idivergence=2;


            /* for thermal calculations the maximum temperature change
               is checked as well */

            if(*ithermal>1){
	        if((ram1[1]>ram2[1])&&(ram[1]>ram2[1])&&(ram[1]>c1[1]*qam[1]))
		    idivergence=1;

		/* if the user has not defined deltmx on the *HEAT
                   TRANSFER card it is set to a large value (1.e30,
                   cf. CalculiX.c); therefore, a comparison of cam[2]
                   with deltmx only makes sense for cam[2]<1.e30 */

		if((cam[2]<1.e30)&&(cam[2]>*deltmx)) idivergence=2;
	    }

	    if(idivergence>0){
		if(*idrct==1){
		    if((*mortar<=1)||((*mortar>1)&&(*iit>200))) {
			
			/* fixed time increments */
			
			printf("\n *ERROR: solution seems to diverge; please try \n");
			printf(" automatic incrementation; program stops\n");
			printf(" best solution and residuals are in the frd file\n\n");
			
			FORTRAN(writestadiv,(istep,iinc,icutb,iit,ttime,time,
						 dtime));
			
			NNEW(fn,double,mt**nk);
			NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
			FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,nk,
					       sti,stn,ipkon,inum,kon,lakon,ne,mi,orab,
					       ielorien,co,itg,ntg,vold,ielmat,thicke,ielprop,prop));
			++*kode;
			
			(*ttime)+=(*time);
			frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
			    kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
			    xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
			    trab,inotr,ntrans,orab,ielorien,norien,description,
			    ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
			    &ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
			    ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,cdn,
			    mortar,cdnr,cdni,nmat,ielprop,prop,sti);
			
			FORTRAN(stop,());
		    }
		}
		else {

                    /* variable time increments */

		    if(qa[2]>0.){
			*dtheta=*dtheta*qa[2];
			printf("increment size decrease requested by a material user routine (through pnewdt)\n\n");
		    }else{
			if(idivergence==1){
			    if((*mortar!=1)||(*icutb!=0)){              // MPADD
                              if(iforceincsize != 1){                   // MPADD
                                *dtheta=*dtheta*df;                     // MPADD
                              }else{                                    // MPADD
                                *dtheta=*sizemaxinc;                    // MPADD
                              }                                         // MPADD
                            }                                           // MPADD
			}else{
			    if(*nmethod==-1){
				*dtheta=*dtheta*cetol/qa[3]*da;
			    }else{
				*dtheta=*dtheta**deltmx/cam[2]*da;
			    }
			}
		    }
		    *dthetaref=*dtheta;
		    printf(" divergence; the increment size is decreased to %e\n",*dtheta**tper);
		    printf(" the increment is reattempted\n\n");

		    FORTRAN(writestadiv,(istep,iinc,icutb,iit,ttime,time,
					     dtime));

		    *istab=0;
		    if(*itp==1){
		      *itp=0;
		      (*inext)--;
		    }

                    /* check whether new increment size is smaller than minimum */

		    if(*dtheta<*tmin){
			printf("\n *ERROR: increment size smaller than minimum\n");
			printf(" best solution and residuals are in the frd file\n\n");
			NNEW(fn,double,mt**nk);
			NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
			FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,
                           nk,sti,stn,ipkon,inum,kon,lakon,ne,mi,orab,
			   ielorien,co,itg,ntg,vold,ielmat,thicke,ielprop,prop));
			++*kode;

			(*ttime)+=(*time);
			frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
			kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
                        xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
                        trab,inotr,ntrans,orab,ielorien,norien,description,
                        ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
                        &ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
                        ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,cdn,
			mortar,cdnr,cdni,nmat,ielprop,prop,sti);

			FORTRAN(stop,());
		    }
		    *icntrl=1;
		    (*icutb)++;
		    if(*mortar==1){
			*kscale=kscalemax;
			printf("\n reducing the constant stiffnesses by a factor of %d \n\n",*kscale);
		    }

                    /* check whether too many cutbacks */

		    if(*icutb>ia){
			printf("\n *ERROR: too many cutbacks\n");
			printf(" best solution and residuals are in the frd file\n\n");
			NNEW(fn,double,mt**nk);
			NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
			FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,
                           nk,sti,stn,ipkon,inum,kon,lakon,ne,mi,orab,
			   ielorien,co,itg,ntg,vold,ielmat,thicke,ielprop,prop));
			++*kode;

			(*ttime)+=(*time);
			frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
			kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
                        xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
                        trab,inotr,ntrans,orab,ielorien,norien,description,
                        ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
                        &ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
                        ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,cdn,
			mortar,cdnr,cdni,nmat,ielprop,prop,sti);

			FORTRAN(stop,());
		    }
		    if(*uncoupled){
		      if(*ithermal==1){
			(ctrl[0])/=4;
		      }
		      *ithermal=3;
		    }

                    /* default value for qa[2] */

		    qa[2]=-1.;

		    *iflagact=0;
		    return;
		}
	    }
	}
	
	/* check for too slow convergence */
	
	if((*iit>=ir)||((*mortar==1)&&(*iit==itf2f))){
	    if(*ithermal!=2){
		iest1=(ITG)ceil(*iit+log(ran*qam[0]/(ram[0]))/
				log(ram[0]/(ram1[0])));
	    }
	    if(*ithermal>1){
		iest2=(ITG)ceil(*iit+log(ran*qam[1]/(ram[1]))/
				log(ram[1]/(ram1[1])));
	    }
	    if(iest1>iest2){iest=iest1;}else{iest=iest2;}
	    if((iest>0)&&(*mortar!=1)){
	    printf(" estimated number of iterations till convergence = %" ITGFORMAT "\n",
		   iest);
	    }
	    if((((iest>ic)||(*iit==ic))&&(*mortar!=1))||((*mortar==1)&&(*iit==itf2f))){
		
		if(*idrct!=1){
		    if((*mortar!=1)||(*icutb!=0)) *dtheta=*dtheta*dc;
		    *dthetaref=*dtheta;
		    if((*mortar==1)&&(*iit==itf2f)){
			printf( "maximum number of iterations for face-to-face contact reached\n");
			printf(" the increment size is decreased to %e\n",*dtheta**tper);
			printf(" the increment is reattempted\n\n");
		    }else{
			printf(" too slow convergence; the increment size is decreased to %e\n",*dtheta**tper);
			printf(" the increment is reattempted\n\n");
		    }

		    FORTRAN(writestadiv,(istep,iinc,icutb,iit,ttime,
					     time,dtime));
		    *istab=0;
		    if(*itp==1){
		      *itp=0;
		      (*inext)--;
		    }

                    /* check whether new increment size is smaller than minimum */

		    if(*dtheta<*tmin){
			printf("\n *ERROR: increment size smaller than minimum\n");
			printf(" best solution and residuals are in the frd file\n\n");
			NNEW(fn,double,mt**nk);
			NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
			FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,
                           nk,sti,stn,ipkon,inum,kon,lakon,ne,mi,orab,
			   ielorien,co,itg,ntg,vold,ielmat,thicke,ielprop,prop));
			++*kode;

			(*ttime)+=(*time);
			frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
			kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
                        xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
                        trab,inotr,ntrans,orab,ielorien,norien,description,
                        ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
                        &ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
                        ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,cdn,
			mortar,cdnr,cdni,nmat,ielprop,prop,sti);

			FORTRAN(stop,());
		    }
		    *icntrl=1;
		    (*icutb)++;
		    if(*mortar==1){
			*kscale=kscalemax;
			printf("\n reducing the constant stiffnesses by a factor of %d \n\n",*kscale);
		    }
//		    if(*mortar==1) *kscale=100;

		    if(*icutb>ia){
			printf("\n *ERROR: too many cutbacks\n");
			printf(" best solution and residuals are in the frd file\n\n");
			NNEW(fn,double,mt**nk);
			NNEW(inum,ITG,*nk);for(k=0;k<*nk;k++) inum[k]=1;
			FORTRAN(storeresidual,(nactdof,b,fn,filab,ithermal,
                           nk,sti,stn,ipkon,inum,kon,lakon,ne,mi,orab,
			   ielorien,co,itg,ntg,vold,ielmat,thicke,ielprop,prop));
			++*kode;

			(*ttime)+=(*time);
			frd(co,nk,kon,ipkon,lakon,ne,vold,stn,inum,nmethod,
			kode,filab,een,t1act,fn,ttime,epn,ielmat,matname,enern,
                        xstaten,nstate_,istep,iinc,ithermal,qfn,mode,noddiam,
                        trab,inotr,ntrans,orab,ielorien,norien,description,
                        ipneigh,neigh,mi,sti,vr,vi,stnr,stni,vmax,stnmax,
                        &ngraph,veold,ener,ne,cs,set,nset,istartset,iendset,
                        ialset,eenmax,fnr,fni,emn,thicke,jobnamec,output,qfx,cdn,
			mortar,cdnr,cdni,nmat,ielprop,prop,sti);

			FORTRAN(stop,());
		    }
		    if(*uncoupled){
		      if(*ithermal==1){
			(ctrl[0])/=4;
		      }
		      *ithermal=3;
		    }

                    /* default value for qa[2] */

		    qa[2]=-1.;

		    *iflagact=0;
		    return;
		}
	    }
	}
	
	printf(" no convergence\n\n");
	
	(*iit)++;
	
    }

    *iflagact=0;
    return;
}
