source: issm/trunk-jpl/src/c/classes/Materials/Matestar.cpp@ 22306

/*!\file Matestar.c
 * \brief: implementation of the Matestar object
 */

#ifdef HAVE_CONFIG_H
        #include <config.h>
#else
#error "Cannot compile with HAVE_CONFIG_H symbol! run configure first!"
#endif

#include "./Matestar.h"
#include "./Materials.h"
#include "../Inputs/Input.h"
#include "../Inputs/Inputs.h"
#include "../Inputs/TriaInput.h"
#include "../Inputs/PentaInput.h"
#include "../Inputs/ControlInput.h"
#include "../Elements/Element.h"
#include "../Elements/Tria.h"
#include "../Elements/Penta.h"
#include "../Params/Parameters.h"
#include "../Vertex.h"
#include "../Hook.h"
#include "../Node.h"
#include "../IoModel.h"
#include "../../shared/shared.h"

/*Matestar constructors and destructor*/
Matestar::Matestar(){/*{{{*/
        this->helement=NULL;
        this->element=NULL;
        return;
}
/*}}}*/
Matestar::Matestar(int matestar_mid,int index, IoModel* iomodel){/*{{{*/

        /*Intermediaries:*/
        int    matestar_eid;

        /*Initialize id*/
        this->mid=matestar_mid;

        /*Hooks: */
        matestar_eid=index+1;
        this->helement=new Hook(&matestar_eid,1);
        this->element=NULL;

        return;
}
/*}}}*/
Matestar::~Matestar(){/*{{{*/
        delete helement;
        return;
}
/*}}}*/

/*Object virtual functions definitions:*/
Object*   Matestar::copy() {/*{{{*/

        /*Output*/
        Matestar* matestar=NULL;

        /*Initialize output*/
        matestar=new Matestar();

        /*copy fields: */
        matestar->mid=this->mid;
        matestar->helement=(Hook*)this->helement->copy();
        matestar->element =(Element*)this->helement->delivers();

        return matestar;
}
/*}}}*/
Material* Matestar::copy2(Element* element_in) {/*{{{*/

        /*Output*/
        Matestar* matestar=NULL;

        /*Initialize output*/
        matestar=new Matestar();

        /*copy fields: */
        matestar->mid=this->mid;
        matestar->helement=(Hook*)this->helement->copy();
        matestar->element =element_in;

        return matestar;
}
/*}}}*/
void      Matestar::DeepEcho(void){/*{{{*/

        _printf_("Matestar:\n");
        _printf_("   mid: " << mid << "\n");
        _printf_("   element:\n");
        helement->Echo();
}               
/*}}}*/
void      Matestar::Echo(void){/*{{{*/

        _printf_("Matestar:\n");
        _printf_("   mid: " << mid << "\n");
        _printf_("   element:\n");
        helement->Echo();
}
/*}}}*/
int       Matestar::Id(void){ return mid; }/*{{{*/
/*}}}*/
void      Matestar::Marshall(char** pmarshalled_data,int* pmarshalled_data_size, int marshall_direction){ /*{{{*/

        if(marshall_direction==MARSHALLING_BACKWARD)helement=new Hook(); 
        
        MARSHALLING_ENUM(MatestarEnum);
        MARSHALLING(mid);
        this->helement->Marshall(pmarshalled_data,pmarshalled_data_size,marshall_direction);
        this->element=(Element*)this->helement->delivers();

}
/*}}}*/
int       Matestar::ObjectEnum(void){/*{{{*/

        return MatestarEnum;

}
/*}}}*/

/*Matestar management*/
void  Matestar::Configure(Elements* elementsin){/*{{{*/

        /*Take care of hooking up all objects for this element, ie links the objects in the hooks to their respective 
         * datasets, using internal ids and offsets hidden in hooks: */
        helement->configure((DataSet*)elementsin);
        this->element  = (Element*)helement->delivers();
}
/*}}}*/
IssmDouble Matestar::GetA(Gauss* gauss){/*{{{*/
        /*
         * A = 1/B^n
         */

        IssmDouble B=this->GetB(gauss);
        IssmDouble n=this->GetN();

        return pow(B,-n);
}
/*}}}*/
IssmDouble Matestar::GetAbar(Gauss* gauss){/*{{{*/
        /*
         * A = 1/B^n
         */

        IssmDouble B=this->GetBbar(gauss);
        IssmDouble n=this->GetN();

        return pow(B,-n);
}
/*}}}*/
IssmDouble Matestar::GetB(Gauss* gauss){/*{{{*/

        /*Output*/
        IssmDouble B;

        Input* B_input = element->GetInput(MaterialsRheologyBEnum); _assert_(B_input);
        B_input->GetInputValue(&B,gauss);
        return B;
}
/*}}}*/
IssmDouble Matestar::GetBbar(Gauss* gauss){/*{{{*/

        /*Output*/
        IssmDouble Bbar;

        Input* B_input = element->GetInput(MaterialsRheologyBbarEnum); _assert_(B_input);
        B_input->GetInputValue(&Bbar,gauss);
        return Bbar;
}
/*}}}*/
IssmDouble Matestar::GetD(Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
IssmDouble Matestar::GetDbar(Gauss* gauss){/*{{{*/

        _error_("not implemented yet");
}
/*}}}*/
IssmDouble Matestar::GetEc(Gauss* gauss){/*{{{*/

        /*Output*/
        IssmDouble Ec;

        Input* Ec_input = element->GetInput(MaterialsRheologyEcEnum); _assert_(Ec_input);
        Ec_input->GetInputValue(&Ec,gauss);
        return Ec;
}
/*}}}*/
IssmDouble Matestar::GetEcbar(Gauss* gauss){/*{{{*/

        /*Output*/
        IssmDouble Ecbar;

        Input* Ecbar_input = element->GetInput(MaterialsRheologyEcbarEnum); _assert_(Ecbar_input);
        Ecbar_input->GetInputValue(&Ecbar,gauss);
        return Ecbar;
}
/*}}}*/
IssmDouble Matestar::GetEs(Gauss* gauss){/*{{{*/

        /*Output*/
        IssmDouble Es;

        Input* Es_input = element->GetInput(MaterialsRheologyEsEnum); _assert_(Es_input);
        Es_input->GetInputValue(&Es,gauss);
        return Es;
}
/*}}}*/
IssmDouble Matestar::GetEsbar(Gauss* gauss){/*{{{*/

        /*Output*/
        IssmDouble Esbar;

        Input* Esbar_input = element->GetInput(MaterialsRheologyEsbarEnum); _assert_(Esbar_input);
        Esbar_input->GetInputValue(&Esbar,gauss);
        return Esbar;
}
/*}}}*/
IssmDouble Matestar::GetN(){/*{{{*/

        /*Output*/
        IssmDouble n=3.0;
        return n;
}
/*}}}*/
void  Matestar::GetViscosity(IssmDouble* pviscosity,IssmDouble eps_eff,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
void  Matestar::GetViscosityBar(IssmDouble* pviscosity,IssmDouble eps_eff,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
void  Matestar::GetViscosityComplement(IssmDouble* pviscosity_complement, IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
void  Matestar::GetViscosityDComplement(IssmDouble* pviscosity_complement, IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
void  Matestar::GetViscosityDerivativeEpsSquare(IssmDouble* pmu_prime, IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
IssmDouble Matestar::GetViscosityGeneral(IssmDouble vx,IssmDouble vy,IssmDouble vz,IssmDouble* dvx,IssmDouble* dvy,IssmDouble* dvz,IssmDouble eps_eff,bool isdepthaveraged,Gauss* gauss){/*{{{*/

        /*output: */
        IssmDouble viscosity;

        /*Intermediaries*/
        IssmDouble epsprime_norm;
        IssmDouble lambdas;
        IssmDouble vmag,dvmag[3];
        IssmDouble B,Ec,Es,E,n;

        /*Calculate velocity magnitude and its derivative*/
        vmag = sqrt(vx*vx+vy*vy+vz*vz);
        if(vmag<1e-12){
                dvmag[0]=0;
                dvmag[1]=0;
                dvmag[2]=0;
        }
        else{
                dvmag[0]=1./(2*sqrt(vmag))*(2*vx*dvx[0]+2*vy*dvy[0]+2*vz*dvz[0]);
                dvmag[1]=1./(2*sqrt(vmag))*(2*vx*dvx[1]+2*vy*dvy[1]+2*vz*dvz[1]);
                dvmag[2]=1./(2*sqrt(vmag))*(2*vx*dvx[2]+2*vy*dvy[2]+2*vz*dvz[2]);
        }

        EstarStrainrateQuantities(&epsprime_norm,vx,vy,vz,vmag,dvx,dvy,dvz,&dvmag[0]);
        lambdas=EstarLambdaS(eps_eff,epsprime_norm);

        /*Get B and enhancement*/
        n=GetN(); _assert_(n>0.);
        if (isdepthaveraged==0.){
                B=GetB(gauss);   _assert_(B>0.);
                Ec=GetEc(gauss); _assert_(Ec>=0.); Es=GetEs(gauss); _assert_(Es>=0.);
        }
        else{
                B=GetBbar(gauss);   _assert_(B>0.);
                Ec=GetEcbar(gauss); _assert_(Ec>=0.);
                Es=GetEsbar(gauss); _assert_(Es>=0.);
        }

        /*Get total enhancement factor E(lambdas)*/
        E = Ec + (Es-Ec)*lambdas*lambdas; _assert_(E>0.);

        /*Compute viscosity*/
        /*if no strain rate, return maximum viscosity*/
        if(eps_eff==0.){
                viscosity = 1.e+14/2.;
                //viscosity = B;
                //viscosity=2.5*pow(10.,17);
        }
        else{
                viscosity = B/(2.*pow(E,1./n)*pow(eps_eff,2./n));
        }

   /*Checks in debugging mode*/
        if(viscosity<=0) _error_("Negative viscosity");

        /*Assign output pointer*/
        return viscosity;
}
/*}}}*/
IssmDouble Matestar::GetViscosity_BGeneral(IssmDouble vx,IssmDouble vy,IssmDouble vz,IssmDouble* dvx,IssmDouble* dvy,IssmDouble* dvz,IssmDouble eps_eff,bool isdepthaveraged,Gauss* gauss){/*{{{*/

        /*Intermediaries*/
        IssmDouble dmudB;
        IssmDouble epsprime_norm;
        IssmDouble lambdas;
        IssmDouble vmag,dvmag[3];
        IssmDouble Ec,Es,E;

        /*Calculate velocity magnitude and its derivative*/
        vmag = sqrt(vx*vx+vy*vy+vz*vz);
        if(vmag<1e-12){
                dvmag[0]=0;
                dvmag[1]=0;
                dvmag[2]=0;
        }
        else{
                dvmag[0]=1./(2*sqrt(vmag))*(2*vx*dvx[0]+2*vy*dvy[0]+2*vz*dvz[0]);
                dvmag[1]=1./(2*sqrt(vmag))*(2*vx*dvx[1]+2*vy*dvy[1]+2*vz*dvz[1]);
                dvmag[2]=1./(2*sqrt(vmag))*(2*vx*dvx[2]+2*vy*dvy[2]+2*vz*dvz[2]);
        }

        EstarStrainrateQuantities(&epsprime_norm,vx,vy,vz,vmag,dvx,dvy,dvz,&dvmag[0]);
        lambdas=EstarLambdaS(eps_eff,epsprime_norm);

        /*Get enhancement*/
        if (isdepthaveraged==0.){
                Ec=GetEc(gauss); _assert_(Ec>=0.);
                Es=GetEs(gauss); _assert_(Es>=0.);
        }
        else{
                Ec=GetEcbar(gauss); _assert_(Ec>=0.);
                Es=GetEsbar(gauss); _assert_(Es>=0.);
        }

        /*Get total enhancement factor E(lambdas)*/
        E = Ec + (Es-Ec)*lambdas*lambdas; _assert_(E>0.);

        /*Compute dmudB*/
        if(eps_eff==0.) dmudB = 0.;
        else            dmudB = 1./(2.*pow(E,1./3.)*pow(eps_eff,2./3.));

        /*Assign output*/
        return dmudB;

}
/*}}}*/
void  Matestar::GetViscosity_B(IssmDouble* pdmudB,IssmDouble eps_eff,Gauss* gauss){/*{{{*/
         _error_("not implemented yet");
}
/*}}}*/
void  Matestar::GetViscosity_D(IssmDouble* pdmudD,IssmDouble eps_eff,Gauss* gauss){/*{{{*/
         _error_("not implemented yet");
}
/*}}}*/
void  Matestar::GetViscosity2dDerivativeEpsSquare(IssmDouble* pmu_prime, IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}
/*}}}*/
void  Matestar::InputUpdateFromConstant(IssmDouble constant, int name){/*{{{*/
        /*Nothing updated yet*/
}
/*}}}*/
void  Matestar::InputUpdateFromConstant(int constant, int name){/*{{{*/
        /*Nothing updated yet*/
}
/*}}}*/
void  Matestar::InputUpdateFromConstant(bool constant, int name){/*{{{*/
        /*Nothing updated yet*/
}
/*}}}*/
void  Matestar::InputUpdateFromMatrixDakota(IssmDouble* matrix, int nrows, int ncols,int name, int type){/*{{{*/
        /*Nothing updated yet*/
}
/*}}}*/
void  Matestar::InputUpdateFromVector(IssmDouble* vector, int name, int type){/*{{{*/

}
/*}}}*/
void  Matestar::InputUpdateFromVectorDakota(IssmDouble* vector, int name, int type){/*{{{*/

}
/*}}}*/
bool Matestar::IsDamage(){/*{{{*/

        _error_("not implemented yet");
}
/*}}}*/
void  Matestar::ResetHooks(){/*{{{*/

        this->element=NULL;

        /*Get Element type*/
        this->helement->reset();

}
/*}}}*/
void  Matestar::SetCurrentConfiguration(Elements* elementsin,Loads* loadsin,Nodes* nodesin,Vertices* verticesin,Materials* materialsin,Parameters* parametersin){/*{{{*/

}
/*}}}*/
void  Matestar::ViscosityBFS(IssmDouble* pdmudB,int dim,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input,Input* vz_input,IssmDouble eps_eff){/*{{{*/

        /*Intermediaries*/
        IssmDouble vx,vy,vz;
        IssmDouble dvx[3],dvy[3],dvz[3];
        bool isdepthaveraged=0.;

        /*Get velocity derivatives in all directions*/
        _assert_(dim>1);
        _assert_(vx_input);
        vx_input->GetInputValue(&vx,gauss);
        vx_input->GetInputDerivativeValue(&dvx[0],xyz_list,gauss);
        _assert_(vy_input);
        vy_input->GetInputValue(&vy,gauss);
        vy_input->GetInputDerivativeValue(&dvy[0],xyz_list,gauss);
        if(dim==3){
                _assert_(vz_input);
                vz_input->GetInputValue(&vz,gauss);
                vz_input->GetInputDerivativeValue(&dvz[0],xyz_list,gauss);
        }
        else{
                vz = 0.;
                dvz[0] = 0.; dvz[1] = 0.; dvz[2] = 0.;
        }

        /*Compute dmudB*/
        *pdmudB=GetViscosity_BGeneral(vx,vy,vz,&dvx[0],&dvy[0],&dvz[0],eps_eff,isdepthaveraged,gauss);
}
/*}}}*/
void  Matestar::ViscosityBHO(IssmDouble* pdmudB,int dim,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input,IssmDouble eps_eff){/*{{{*/

        /*Intermediaries*/
        IssmDouble vx,vy,vz;
        IssmDouble dvx[3],dvy[3],dvz[3];
        bool isdepthaveraged=0.;

        /*Get velocity derivatives in all directions*/
        _assert_(dim==2 || dim==3);
        _assert_(vx_input);
        vx_input->GetInputValue(&vx,gauss);
        vx_input->GetInputDerivativeValue(&dvx[0],xyz_list,gauss);
        if(dim==3){
                _assert_(vy_input);
                vy_input->GetInputValue(&vy,gauss);
                vy_input->GetInputDerivativeValue(&dvy[0],xyz_list,gauss);
        }
        else{
                dvx[2] = 0.;
                vy = 0.;
                dvy[0] = 0.; dvy[1] = 0.; dvy[2] = 0.;
        }
        vz = 0.;
        dvz[0] = 0.; dvz[1] = 0.; dvz[2] = -dvx[0]-dvy[1];

        /*Compute viscosity*/
        *pdmudB=GetViscosity_BGeneral(vx,vy,vz,&dvx[0],&dvy[0],&dvz[0],eps_eff,isdepthaveraged,gauss);
}/*}}}*/
void  Matestar::ViscosityBSSA(IssmDouble* pdmudB,int dim,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input,IssmDouble eps_eff){/*{{{*/
        /*Intermediaries*/
        IssmDouble vx,vy,vz;
        IssmDouble dvx[3],dvy[3],dvz[3];
        bool isdepthaveraged=1.;

        /*Get velocity derivatives in all directions*/
        _assert_(dim==1 || dim==2);
        _assert_(vx_input);
        vx_input->GetInputValue(&vx,gauss);
        vx_input->GetInputDerivativeValue(&dvx[0],xyz_list,gauss);
        if(dim==2){
                _assert_(vy_input);
                vy_input->GetInputValue(&vy,gauss);
                vy_input->GetInputDerivativeValue(&dvy[0],xyz_list,gauss);
        }
        else{
                dvx[1] = 0.;
                dvx[2] = 0.;
                vy = 0.;
                dvy[0] = 0.; dvy[1] = 0.; dvy[2] = 0.;
        }
        dvx[2] = 0.;
        dvy[2] = 0.;
        vz = 0.;
        dvz[0] = 0.; dvz[1] = 0.; dvz[2] = -dvx[0]-dvy[1];

        /*Compute viscosity*/
        *pdmudB=GetViscosity_BGeneral(vx,vy,vz,&dvx[0],&dvy[0],&dvz[0],eps_eff,isdepthaveraged,gauss);
}/*}}}*/
void  Matestar::ViscosityFS(IssmDouble* pviscosity,int dim,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input,Input* vz_input){/*{{{*/

        /*Intermediaries*/
        IssmDouble vx,vy,vz;
        IssmDouble dvx[3],dvy[3],dvz[3];
        IssmDouble epsilon3d[6]; /* epsilon=[exx,eyy,ezz,exy,exz,eyz];*/
        IssmDouble epsilon2d[3]; /* epsilon=[exx,eyy,exy];*/
        IssmDouble eps_eff,eps0=1.e-27;
        bool isdepthaveraged=0.;

        /*Get velocity derivatives in all directions*/
        _assert_(dim>1);
        _assert_(vx_input);
        vx_input->GetInputValue(&vx,gauss);
        vx_input->GetInputDerivativeValue(&dvx[0],xyz_list,gauss);
        _assert_(vy_input);
        vy_input->GetInputValue(&vy,gauss);
        vy_input->GetInputDerivativeValue(&dvy[0],xyz_list,gauss);
        if(dim==3){
                _assert_(vz_input);
                vz_input->GetInputValue(&vz,gauss);
                vz_input->GetInputDerivativeValue(&dvz[0],xyz_list,gauss);
        }
        else{
                vz = 0.;
                dvz[0] = 0.; dvz[1] = 0.; dvz[2] = 0.;
        }

        if(dim==3){
      /* eps_eff^2 = exx^2 + eyy^2 + exy^2 + exz^2 + eyz^2 + exx*eyy */
                element->StrainRateFS(&epsilon3d[0],xyz_list,gauss,vx_input,vy_input,vz_input);
                eps_eff = sqrt(epsilon3d[0]*epsilon3d[0] + epsilon3d[1]*epsilon3d[1] + epsilon3d[3]*epsilon3d[3] +  epsilon3d[4]*epsilon3d[4] + epsilon3d[5]*epsilon3d[5] + epsilon3d[0]*epsilon3d[1]+eps0*eps0);
        }
        else{
                /* eps_eff^2 = 1/2 ( exx^2 + eyy^2 + 2*exy^2 )*/
                element->StrainRateSSA(&epsilon2d[0],xyz_list,gauss,vx_input,vy_input);
                eps_eff = 1./sqrt(2.)*sqrt(epsilon2d[0]*epsilon2d[0] + epsilon2d[1]*epsilon2d[1] + 2.*epsilon2d[2]*epsilon2d[2]);
        }

        /*Compute viscosity*/
        *pviscosity=GetViscosityGeneral(vx,vy,vz,&dvx[0],&dvy[0],&dvz[0],eps_eff,isdepthaveraged,gauss);
}
/*}}}*/
void  Matestar::ViscosityFSDerivativeEpsSquare(IssmDouble* pmu_prime,IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        this->GetViscosityDerivativeEpsSquare(pmu_prime,epsilon,gauss);
}/*}}}*/
void  Matestar::ViscosityHO(IssmDouble* pviscosity,int dim,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input){/*{{{*/

        /*Intermediaries*/
        IssmDouble vx,vy,vz;
        IssmDouble dvx[3],dvy[3],dvz[3];
        IssmDouble epsilon3d[5]; /* epsilon=[exx,eyy,exy,exz,eyz];*/
        IssmDouble epsilon2d[5]; /* epsilon=[exx,exy];*/
        IssmDouble eps_eff;
        bool isdepthaveraged=0.;

   if(dim==3){
                /* eps_eff^2 = exx^2 + eyy^2 + exy^2 + exz^2 + eyz^2 + exx*eyy */
                element->StrainRateHO(&epsilon3d[0],xyz_list,gauss,vx_input,vy_input);
                eps_eff = sqrt(epsilon3d[0]*epsilon3d[0] + epsilon3d[1]*epsilon3d[1] + epsilon3d[2]*epsilon3d[2] +  epsilon3d[3]*epsilon3d[3] + epsilon3d[4]*epsilon3d[4] + epsilon3d[0]*epsilon3d[1]);
        }
        else{
                /* eps_eff^2 = 1/2 (2*exx^2 + 2*exy^2 ) (since eps_zz = - eps_xx)*/
                element->StrainRateHO2dvertical(&epsilon2d[0],xyz_list,gauss,vx_input,vy_input);
                eps_eff = 1./sqrt(2.)*sqrt(2*epsilon2d[0]*epsilon2d[0] + 2*epsilon2d[1]*epsilon2d[1]);
        }

        /*Get velocity derivatives in all directions*/
        _assert_(dim==2 || dim==3);
        _assert_(vx_input);
        vx_input->GetInputValue(&vx,gauss);
        vx_input->GetInputDerivativeValue(&dvx[0],xyz_list,gauss);
        if(dim==3){
                _assert_(vy_input);
                vy_input->GetInputValue(&vy,gauss);
                vy_input->GetInputDerivativeValue(&dvy[0],xyz_list,gauss);
        }
        else{
                dvx[2] = 0.;
                vy = 0.;
                dvy[0] = 0.; dvy[1] = 0.; dvy[2] = 0.;
        }
        vz = 0.;
        dvz[0] = 0.; dvz[1] = 0.; dvz[2] = -dvx[0]-dvy[1];

        /*Compute viscosity*/
        *pviscosity=GetViscosityGeneral(vx,vy,vz,&dvx[0],&dvy[0],&dvz[0],eps_eff,isdepthaveraged,gauss);
}/*}}}*/
void  Matestar::ViscosityHODerivativeEpsSquare(IssmDouble* pmu_prime,IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}/*}}}*/
void  Matestar::ViscosityL1L2(IssmDouble* pviscosity,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input,Input* surface_input){/*{{{*/
        _error_("not implemented yet");
}/*}}}*/
void  Matestar::ViscositySSA(IssmDouble* pviscosity,int dim,IssmDouble* xyz_list,Gauss* gauss,Input* vx_input,Input* vy_input){/*{{{*/

        /*Intermediaries*/
        IssmDouble vx,vy,vz;
        IssmDouble dvx[3],dvy[3],dvz[3];
        IssmDouble epsilon2d[3];/* epsilon=[exx,eyy,exy]; */
        IssmDouble epsilon1d;   /* epsilon=[exx];         */
        IssmDouble eps_eff;
        bool isdepthaveraged=1.;

        /*Get velocity derivatives in all directions*/
        _assert_(dim==1 || dim==2);
        _assert_(vx_input);
        vx_input->GetInputValue(&vx,gauss);
        vx_input->GetInputDerivativeValue(&dvx[0],xyz_list,gauss);
        if(dim==2){
                _assert_(vy_input);
                vy_input->GetInputValue(&vy,gauss);
                vy_input->GetInputDerivativeValue(&dvy[0],xyz_list,gauss);
        }
        else{
                dvx[1] = 0.;
                dvx[2] = 0.;
                vy = 0.;
                dvy[0] = 0.; dvy[1] = 0.; dvy[2] = 0.;
        }
        dvx[2] = 0.;
        dvy[2] = 0.;
        vz = 0.;
        dvz[0] = 0.; dvz[1] = 0.; dvz[2] = -dvx[0]-dvy[1];

   if(dim==2){
                /* eps_eff^2 = exx^2 + eyy^2 + exy^2 + exx*eyy*/
                element->StrainRateSSA(&epsilon2d[0],xyz_list,gauss,vx_input,vy_input);
                eps_eff = sqrt(epsilon2d[0]*epsilon2d[0] + epsilon2d[1]*epsilon2d[1] + epsilon2d[2]*epsilon2d[2] + epsilon2d[0]*epsilon2d[1]);
        }
        else{
                /* eps_eff^2 = exx^2*/
                element->StrainRateSSA1d(&epsilon1d,xyz_list,gauss,vx_input);
                eps_eff = fabs(epsilon1d);
        }

        /*Compute viscosity*/
        *pviscosity=GetViscosityGeneral(vx,vy,vz,&dvx[0],&dvy[0],&dvz[0],eps_eff,isdepthaveraged,gauss);
}/*}}}*/
void  Matestar::ViscositySSADerivativeEpsSquare(IssmDouble* pmu_prime,IssmDouble* epsilon,Gauss* gauss){/*{{{*/
        _error_("not implemented yet");
}/*}}}*/