# Oldroyd-B model freefem++ code bugs and issues: Assertion fail

**URL:** <https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767>\
**Category:** General Discussion\
**Created:** [February 24, 2025, 11:19am UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767 "2025-02-24T11:19:30Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![ozil101](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/ozil101/32/1820_2.png) [@ozil101](https://community.freefem.org/u/ozil101)\
**Post date:** [February 24, 2025, 11:19am UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/1 "2025-02-24T11:19:30Z")

</div>

Hi all,

I built up a code for 2D bearing lubrication problem, I adjusted all the parameters & conditions into the standard ones of this benchmark problem, however I always get this issue:

{ 139 : } sizestack + 1024 =20004 ( 18980 )

– mesh: Nb of Triangles = 4382, Nb of Vertices 2316  
current line = 50  
Assertion fail : (!half)  
line :1263, in file …/femlib/HashMatrix.cpp  
Assertion fail : (!half)  
line :1263, in file …/femlib/HashMatrix.cpp  
err code 6 , mpirank 0}

what could be the reason and the solution?

best,  
Hussein.

---

<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [February 24, 2025, 12:27pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/2 "2025-02-24T12:27:14Z")

</div>

Without the code it is difficult,It you say the building matrix is full but you store just half.  
So You do strange thing.

---

<div class="post-metadata">

**Author:** ![ozil101](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/ozil101/32/1820_2.png) [@ozil101](https://community.freefem.org/u/ozil101)\
**Post date:** [February 24, 2025, 3:16pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/3 "2025-02-24T15:16:56Z")

</div>

Thank you Prof for your reply, this is the code. I tried to implement the conditions within this paper [[https://onlinelibrary.wiley.com/doi/10.1002/zamm.202300095](https://onlinelibrary.wiley.com/doi/10.1002/zamm.202300095)  
[Bmmpff\_bearing\_lubrication.edp](https://community.freefem.org/uploads/short-url/lJgdgZ2Iv7vzj5lNHRITVXXlrqp.edp) (4.8 KB)  
].

---

<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [February 24, 2025, 3:40pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/4 "2025-02-24T15:40:45Z")

</div>

I have run you script , I a see a first mistake the boundary condition on Oldroyd… are take on table 4 but the label 4 do not existe =\> full Neumann Boundary condition.

---

<div class="post-metadata">

**Author:** ![ozil101](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/ozil101/32/1820_2.png) [@ozil101](https://community.freefem.org/u/ozil101)\
**Post date:** [February 27, 2025, 12:02pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/5 "2025-02-27T12:02:17Z")

</div>

Thank you the code works now very well. However, I COULD NOT manage to apply some FEM stabilization techniques (i.e. SUPG, PGP, DEVSS) on this benchmark I always got an operator error especially when applying DEVSS (using least-square scheme by adding auxiliary velocity gradient variables: (G11, G12, G21, G22)) scheme like this:  
{  
{ 105 : solve ComputeG(G11, G12, G21, G22) =  
106 : int2d(Th)(G11 \* w - dx(u) \* w) error operator - \<10LinearCombI7MGauche4C\_F0E\>,   
List of choices  
( : , )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<14Matrice\_CreuseISt7complexIdEE\>, \<14Matrice\_CreuseISt7complexIdEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<14Matrice\_CreuseISt7complexIdEE\>, \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\>, \<14Matrice\_CreuseISt7complexIdEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\>, \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<14Matrice\_CreuseIdE\>, \<14Matrice\_CreuseIdE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<14Matrice\_CreuseIdE\>, \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\>, \<14Matrice\_CreuseIdE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\>, \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> )  
( \<10FormLinear\> : \<10FormLinear\> )  
( \<12FormBilinear\> : \<12FormBilinear\> )  
( \<6C\_args\> : \<6C\_args\>, \<10FormLinear\> )  
( \<6C\_args\> : \<6C\_args\>, \<12FormBilinear\> )  
( \<10LinearCombI7MGauche4C\_F0E\> : \<10LinearCombI7MGauche4C\_F0E\>, \<10LinearCombI7MGauche4C\_F0E\> )  
( \<10LinearCombI6MDroit4C\_F0E\> : \<10LinearCombI6MDroit4C\_F0E\>, \<10LinearCombI6MDroit4C\_F0E\> )  
( \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> : \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\>, \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> )  
( \<10LinearCombI7MGauche4C\_F0E\> : \<10LinearCombI7MGauche4C\_F0E\> )  
( \<10LinearCombI6MDroit4C\_F0E\> : \<10LinearCombI6MDroit4C\_F0E\> )  
( \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> : \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> )  
( \<4C\_F0\> : \<12TransE\_Array\>, \<12TransE\_Array\> )  
( \<4C\_F0\> : \<7E\_Array\>, \<12TransE\_Array\> )  
( \<4C\_F0\> : \<7E\_Array\>, \<7E\_Array\> )  
( \<4C\_F0\> : \<12TransE\_Array\>, \<7E\_Array\> )  
( \<12Add\_Mulc\_KN\_ISt7complexIdEE\> : \<8Mulc\_KN\_ISt7complexIdEE\>, \<3KN\_ISt7complexIdEE\> )  
( \<12Add\_Mulc\_KN\_ISt7complexIdEE\> : \<3KN\_ISt7complexIdEE\>, \<8Mulc\_KN\_ISt7complexIdEE\> )  
( \<12Add\_Mulc\_KN\_ISt7complexIdEE\> : \<8Mulc\_KN\_ISt7complexIdEE\>, \<8Mulc\_KN\_ISt7complexIdEE\> )  
( \<8Mulc\_KN\_ISt7complexIdEE\> : \<3KN\_ISt7complexIdEE\> )  
( \<7Sub\_KN\_ISt7complexIdEE\> : \<3KN\_ISt7complexIdEE\>, \<3KN\_ISt7complexIdEE\> )  
( \<12Add\_Mulc\_KN\_IdE\> : \<8Mulc\_KN\_IdE\>, \<3KN\_IdE\> )  
( \<12Add\_Mulc\_KN\_IdE\> : \<3KN\_IdE\>, \<8Mulc\_KN\_IdE\> )  
( \<12Add\_Mulc\_KN\_IdE\> : \<8Mulc\_KN\_IdE\>, \<8Mulc\_KN\_IdE\> )  
( \<8Mulc\_KN\_IdE\> : \<3KN\_IdE\> )  
( \<7Sub\_KN\_IdE\> : \<3KN\_IdE\>, \<3KN\_IdE\> )  
( \<12Add\_Mulc\_KN\_IlE\> : \<8Mulc\_KN\_IlE\>, \<3KN\_IlE\> )  
( \<12Add\_Mulc\_KN\_IlE\> : \<3KN\_IlE\>, \<8Mulc\_KN\_IlE\> )  
( \<12Add\_Mulc\_KN\_IlE\> : \<8Mulc\_KN\_IlE\>, \<8Mulc\_KN\_IlE\> )  
( \<8Mulc\_KN\_IlE\> : \<3KN\_IlE\> )  
( \<7Sub\_KN\_IlE\> : \<3KN\_IlE\>, \<3KN\_IlE\> )  
( : )  
( : )  
( : )  
( : **, )  
( : , )  
( : , )  
( : , )  
( : , )  
( : , )  
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( : , )**

 

Error line number 106, in file …edp, before token )

current line = 106  
Compile error :  
line number :106, )  
error Compile error :  
line number :106, )  
code = 1 mpirank: 0  
}

---

<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [February 27, 2025, 12:31pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/6 "2025-02-27T12:31:57Z")

</div>

Remember, I, freefem with solve variation form with unknown function and test function, and in the example no test function so we get an error!

---

<div class="post-metadata">

**Author:** ![ozil101](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/ozil101/32/1820_2.png) [@ozil101](https://community.freefem.org/u/ozil101)\
**Post date:** [February 27, 2025, 1:10pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/7 "2025-02-27T13:10:51Z")

</div>

Yes, indeed Prof. I also re-define my constitutive Oldroyd-B model solution as this and also defined the initial variable in my fe-space and test function (I use ‘w’ test function as the same old square-root conformation solution and defined G11old, G11, G12old, G12, G13old, G21, G14old, G22):  
Full code:  
{  
int outer = 1;  
int inner = 2;

border a(t=0, 2_pi){x=cos(t); y=sin(t); label=outer;}  
border b(t=0, 2_pi){x=0.55+0.4_cos(t); y=0.35_sin(t); label=inner;}

plot(a(50) + b(30));

mesh Th = buildmesh(a(350) + b(-300));  
plot(Th, fill=true, ps=“Bmmpff\_Bearing\_Lubrication\_Domain.eps”);

fespace Vh(Th, P1);  
fespace Mh(Th, P1);

real dt = 0.005, re = 500.0, Wi = 2.75;  
real al=0.5, dT=dt/2.0, t=0, T=30.0, ee=0.00001, L2errortau11, L2errortau12, L2erroru;  
real gamma = 0.1, mur = 0.50 / re, sigmanf = 0.5, B0 = 1.1;  
real rhonf = 0.25, j = 0.1;  
real munf = 0.525; // fluid dynamic viscosity value  
real Omega = 0.1025; // initial fluid angular velocity variable  
real lambda = 0.505; // extra stress tensor parameter  
real beta=1.0/9.0;  
real epsilon = 0.314;

real nv = Th.nv;  
real nt = Th.nt;

Mh p, q;  
Vh w, u, v, omega, tau11, tau12, tau21, tau22, G11, G12, G21, G22;  
Vh uT, vT, omegaT, uTT, vTT, omegaTT;  
Vh tau11old, tau12old, tau21old, tau22old, uold, vold, pold, omegaold, G11old, G12old, G13old, G14old;

u = -0.5 \* Omega \* sin(epsilon);  
v = 0.5 \* Omega \* cos(epsilon);  
omega = 200;

for (int m = 0; m \<= T / dt; m++) {  
Vh uold = u, vold = v, pold = p, omegaold = omega;  
pold = p;

```
//Intermediate Velocity Solutions//

solve Adual4unon(uT, w) =
    int2d(Th)(rhonf * uT * w / dt)
    + int2d(Th)(munf * (dx(uT) * dx(w) + dy(uT) * dy(w)))
    - int2d(Th)((rhonf * convect([uold, vold], -dt, uold) * w) / dt)
    + int2d(Th)(2 * rhonf * Omega * (dy(vold) * w - dx(uold) * w))
    - int2d(Th)(sigmanf * B0^2 * uT * w)
    + int2d(Th)(lambda * (dx(uold) * dx(w) + dy(uold) * dy(w)))  
    + on(outer, uT = -Omega * y)
    + on(inner, uT = 0); // No flow inside the small circle

solve Adual4vnon(vT, w) =
    int2d(Th)(rhonf * vT * w / dt)
    + int2d(Th)(munf * (dx(vT) * dx(w) + dy(vT) * dy(w)))
    - int2d(Th)((rhonf * convect([uold, vold], -dt, vold) * w) / dt)
    + int2d(Th)(2 * rhonf * Omega * (dy(uold) * w - dx(vold) * w))
    - int2d(Th)(sigmanf * B0^2 * vT * w)
    + int2d(Th)(lambda * (dx(vold) * dx(w) + dy(vold) * dy(w)))
    + on(outer, vT = -Omega * x)
    + on(inner, vT = 0);

solve Adual4omeganon(omegaT, w) =
    int2d(Th)(omegaT * w / dt)
    - int2d(Th)(convect([uold, vold], -dt, omegaold) * w / dt)
    + on(outer, omegaT = B0)
    + on(inner, omegaT = 0); // No microrotation inside the small circle

//Updated Velocity Solutions (u,v,omega)//

solve pb4p(p, q) =
    int2d(Th)(dx(p) * dx(q) + dy(p) * dy(q))
    + int2d(Th)(((dx(uT) + dy(vT)) * q) / dt);

solve pb4u(u, w) =
    int2d(Th)((dx(u) * dx(w) + dy(u) * dy(w)) / re + u * w / dt)
    - int2d(Th)(uT * w / dt - dx(p) * w)
    + on(outer, u = 0)
    + on(inner, u = 0); // No flow inside the small circle

solve pb4v(v, w) =
    int2d(Th)((dx(v) * dx(w) + dy(v) * dy(w)) / re + v * w / dt)
    - int2d(Th)(vT * w / dt - dy(p) * w)
    + on(outer, v = 0)
    + on(inner, v = 0); // No flow inside the small circle

solve pb4omega(omega, w) =
    int2d(Th)((dx(omega) * dx(w) + dy(omega) * dy(w)) / re + omega * w / dt)
    - int2d(Th)(omegaT * w / dt)
    + on(outer, omega = 0)
    + on(inner, omega = 0); // No microrotation inside the small circle

```

Vh tau11old=tau11,tau12old=tau12,tau21old=tau21,tau22old=tau22;  
Vh G11old=G11, G12old=G12, G13old=G21, G14old=G22;

```
  // **********************************solve the constitutive model equation********************* //

```

// define DEVSS aux. variable G  
solve ComputeG(G11, G12, G21, G22) =  
int2d(Th)(G11 \* w - dx(u) \* w)

- int2d(Th)(G12 \* w - dy(u) \* w)
- int2d(Th)(G21 \* w - dx(v) \* w)
- int2d(Th)(G22 \* w - dy(v) \* w);

// include DEVSS stabilization  
solve Oldroyd11 (tau11, w) =  
int2d(Th)(tau11 \* w / dt)

- int2d(Th)(-1/dt \* convect([u, v], -dt, tau11old) \* w)

- int2d(Th)(((1-beta) \* 2 / Wi \* G11 + 2 \* (G11 \* tau11old + G12 \* tau12old) - tau11old / Wi) \* w)

- int1d(Th, inner)(tau11 \* w)
- int1d(Th, outer)(tau11 \* w);

solve Oldroyd12 (tau12, w) =  
int2d(Th)(tau12 \* w / dt)

- int2d(Th)(-1/dt \* convect([u, v], -dt, tau12old) \* w)

- int2d(Th)(((1-beta) / Wi \* (G12 + G21) + (G11 \* tau12old + G12 \* tau22old + G21 \* tau12old + G22 \* tau11old)) \* w - w \* tau12old / Wi)

- int1d(Th, inner)(tau12 \* w)
- int1d(Th, outer)(tau12 \* w);

tau21 = tau12;

solve Oldroyd22 (tau22, w) =  
int2d(Th)(tau22 \* w / dt)

- int2d(Th)(-1/dt \* convect([u, v], -dt, tau22old) \* w)

- int2d(Th)(((1-beta) \* 2 / Wi \* G22 + 2 \* (G21 \* tau12old + G22 \* tau22old) - tau22old / Wi) \* w)

- int1d(Th, inner)(tau22 \* w)
- int1d(Th, outer)(tau22 \* w);

t=t+dt;

// plot(u,fill=1,cmm=“t=”+t + “, min=” + u.min + “, max=” + u.max);

```
L2errortau11=sqrt(int2d(Th)((tau11-2.0*Wi*(1-beta)*(0.16*(1.0-2.0*y)*(1.0-2.0*y)))^2))
/sqrt(int2d(Th)((2.0*Wi*(1-beta)*(0.16*(1.0-2.0*y)*(1.0-2.0*y)))^2));
L2errortau12=sqrt(int2d(Th)((tau12-(1-beta)*(0.4*(1.0-2.0*y)))^2))/sqrt(int2d(Th)(((1-beta)*(0.4*(1.0-2.0*y)))^2));
 L2erroru=sqrt(int2d(Th)((u-0.4*y*(1-y))^2))/sqrt(int2d(Th)((0.4*y*(1-y))^2));
cout <<" L2tau11= " <<L2errortau11<<"L2tau12= "<<L2errortau12<<" L2u="<<L2erroru<< endl;

```

// Plot each time-step of the 9 components  
}  
Error:  
{  
104 : // define DEVSS aux. variable G  
105 : solve ComputeG(G11, G12, G21, G22) =  
106 : int2d(Th)(G11 \* w - dx(u) \* w) error operator - \<10LinearCombI7MGauche4C\_F0E\>,   
List of choices  
( : , )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<14Matrice\_CreuseISt7complexIdEE\>, \<14Matrice\_CreuseISt7complexIdEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<14Matrice\_CreuseISt7complexIdEE\>, \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\>, \<14Matrice\_CreuseISt7complexIdEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\>, \<NSt7\_\_cxx114listISt5tupleIJSt7complexIdEP13VirtualMatrixIiS3\_EbEESaIS7\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<14Matrice\_CreuseIdE\>, \<14Matrice\_CreuseIdE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<14Matrice\_CreuseIdE\>, \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\>, \<14Matrice\_CreuseIdE\> )  
( \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> : \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\>, \<NSt7\_\_cxx114listISt5tupleIJdP13VirtualMatrixIidEbEESaIS5\_EEE\> )  
( \<10FormLinear\> : \<10FormLinear\> )  
( \<12FormBilinear\> : \<12FormBilinear\> )  
( \<6C\_args\> : \<6C\_args\>, \<10FormLinear\> )  
( \<6C\_args\> : \<6C\_args\>, \<12FormBilinear\> )  
( \<10LinearCombI7MGauche4C\_F0E\> : \<10LinearCombI7MGauche4C\_F0E\>, \<10LinearCombI7MGauche4C\_F0E\> )  
( \<10LinearCombI6MDroit4C\_F0E\> : \<10LinearCombI6MDroit4C\_F0E\>, \<10LinearCombI6MDroit4C\_F0E\> )  
( \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> : \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\>, \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> )  
( \<10LinearCombI7MGauche4C\_F0E\> : \<10LinearCombI7MGauche4C\_F0E\> )  
( \<10LinearCombI6MDroit4C\_F0E\> : \<10LinearCombI6MDroit4C\_F0E\> )  
( \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> : \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\> )  
( \<4C\_F0\> : \<12TransE\_Array\>, \<12TransE\_Array\> )  
( \<4C\_F0\> : \<7E\_Array\>, \<12TransE\_Array\> )  
( \<4C\_F0\> : \<7E\_Array\>, \<7E\_Array\> )  
( \<4C\_F0\> : \<12TransE\_Array\>, \<7E\_Array\> )  
( \<12Add\_Mulc\_KN\_ISt7complexIdEE\> : \<8Mulc\_KN\_ISt7complexIdEE\>, \<3KN\_ISt7complexIdEE\> )  
( \<12Add\_Mulc\_KN\_ISt7complexIdEE\> : \<3KN\_ISt7complexIdEE\>, \<8Mulc\_KN\_ISt7complexIdEE\> )  
( \<12Add\_Mulc\_KN\_ISt7complexIdEE\> : \<8Mulc\_KN\_ISt7complexIdEE\>, \<8Mulc\_KN\_ISt7complexIdEE\> )  
( \<8Mulc\_KN\_ISt7complexIdEE\> : \<3KN\_ISt7complexIdEE\> )  
( \<7Sub\_KN\_ISt7complexIdEE\> : \<3KN\_ISt7complexIdEE\>, \<3KN\_ISt7complexIdEE\> )  
( \<12Add\_Mulc\_KN\_IdE\> : \<8Mulc\_KN\_IdE\>, \<3KN\_IdE\> )  
( \<12Add\_Mulc\_KN\_IdE\> : \<3KN\_IdE\>, \<8Mulc\_KN\_IdE\> )  
( \<12Add\_Mulc\_KN\_IdE\> : \<8Mulc\_KN\_IdE\>, \<8Mulc\_KN\_IdE\> )  
( \<8Mulc\_KN\_IdE\> : \<3KN\_IdE\> )  
( \<7Sub\_KN\_IdE\> : \<3KN\_IdE\>, \<3KN\_IdE\> )  
( \<12Add\_Mulc\_KN\_IlE\> : \<8Mulc\_KN\_IlE\>, \<3KN\_IlE\> )  
( \<12Add\_Mulc\_KN\_IlE\> : \<3KN\_IlE\>, \<8Mulc\_KN\_IlE\> )  
( \<12Add\_Mulc\_KN\_IlE\> : \<8Mulc\_KN\_IlE\>, \<8Mulc\_KN\_IlE\> )  
( \<8Mulc\_KN\_IlE\> : \<3KN\_IlE\> )  
( \<7Sub\_KN\_IlE\> : \<3KN\_IlE\>, \<3KN\_IlE\> )  
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Error line number 106, in file …edp, before token )

current line = 106  
Compile error :  
line number :106, )  
error Compile error :  
line number :106, )  
code = 1 mpirank: 0  
}

---

<div class="post-metadata">

**Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\
**Post date:** [February 28, 2025, 5:17pm UTC](https://community.freefem.org/t/oldroyd-b-model-freefem-code-bugs-and-issues-assertion-fail/3767/8 "2025-02-28T17:17:17Z")

</div>

I think you can do simply

```auto
solve ComputeG11(G11, w) = int2d(Th)(G11 * w) - int2d(Th)(dx(u) * w);
solve ComputeG12(G12, w) = int2d(Th)(G12 * w) - int2d(Th)(dy(u) * w);
solve ComputeG21(G21, w) = int2d(Th)(G21 * w) - int2d(Th)(dx(v) * w);
solve ComputeG22(G22, w) = int2d(Th)(G22 * w) - int2d(Th)(dy(v) * w);

```

or even simpler by interpolation  
`G11=dx(u);G12=dy(u);G21=dx(v);G22=dy(v);`

Moreover the cross term of the symmetric product should be  
`(G11 * tau12old + G12 * tau22old + G21 * tau11old + G22 * tau12old))`  
instead of `(G11 * tau12old + G12 * tau22old + G21 * tau12old + G22 * tau11old))`