# Order of variables in matrix generated with varf with a \[P1, P1, P0\] fespace **URL:** https://community.freefem.org/t/order-of-variables-in-matrix-generated-with-varf-with-a-p1-p1-p0-fespace/3489 **Category:** General Discussion **Created:** [September 17, 2024, 2:51pm UTC](https://community.freefem.org/t/order-of-variables-in-matrix-generated-with-varf-with-a-p1-p1-p0-fespace/3489 "2024-09-17T14:51:22Z") **Posts on this page:** 1 **Showing post:** 1
### Author: ![djahid](https://avatars.discourse-cdn.com/v4/letter/d/bbe5ce/32.png) [@djahid](https://community.freefem.org/u/djahid) #### Post date: [September 17, 2024, 2:51pm UTC](https://community.freefem.org/t/order-of-variables-in-matrix-generated-with-varf-with-a-p1-p1-p0-fespace/3489/1 "2024-09-17T14:51:22Z")
Hello, I’m trying to compare the matrix generated from the following code with another code I have that solves the same problem ```auto mesh Th=square(2, 2); fespace Xh(Th,P1); fespace Mh(Th,P0); fespace XhxXhxMh(Th,[P1,P1,P0]); varf vfStokes ([u1,u2,p],[v1,v2,q]) = int2d(Th)( alpha*( u1*v1 + u2*v2) + nu * ( dx(u1)*dx(v1) + dy(u1)*dy(v1) + dx(u2)*dx(v2) + dy(u2)*dy(v2) ) + p*q*(1e-4) - p*dx(v1) - p*dy(v2) - dx(u1)*q - dy(u2)*q ); varf b([u1,u2,p],[v1,v2,q]) = int2d(Th)( u1*v1+u2*v2+p*q*0.) ; matrix A= vfStokes(XhxXhxMh, XhxXhxMh, solver="SPARSESOLVER", factorize=0); matrix B= b(XhxXhxMh, XhxXhxMh, solver=CG, eps=1e-20); ``` Here the A matrix is: ```auto 0: 1 0 0.25 -0.5 0 0 0 0 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1: 0 1 -0.25 0 -0.5 0 0 0 0 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2: 0.25 -0.25 1.25e-05 -0.25 0 0 0 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3: -0.5 0 -0.25 2 0 0.25 0 0 0 0 0 -0.5 0 -1 0 0 0 0 0 0 0 0 0 0 0 0 4: 0 -0.5 0 0 2 -0.25 -0.25 0 0 0 0 0 -0.5 0 -1 0 0 0 0 0 0 0 0 0 0 0 5: 0 0 0 0.25 -0.25 1.25e-05 0 0 0 0 0 -0.25 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 6: 0 0 0 0 -0.25 0 1.25e-05 0 0.25 0 0 0 0 -0.25 0.25 0 0 0 0 0 0 0 0 0 0 0 7: 0 0 0 0 0 0 0 1.25e-05 0.25 -0.25 0 0 0 -0.25 0 0 0.25 0 0 0 0 0 0 0 0 0 8: -0.5 0 0 0 0 0 0.25 0.25 2 0 0 0 0 -1 0 -0.5 0 0 0 0 0 0 0 0 0 0 9: 0 -0.5 0.25 0 0 0 0 -0.25 0 2 0 0 0 0 -1 0 -0.5 0 0 0 0 0 0 0 0 0 10: 0 0 0 0 0 0 0 0 0 0 1.25e-05 0 -0.25 0.25 0 0 0 0 0 -0.25 0.25 0 0 0 0 0 11: 0 0 0 -0.5 0 -0.25 0 0 0 0 0 1 0 0 0 0 0 0 0 -0.5 0 0 0 0 0 0 12: 0 0 0 0 -0.5 0 0 0 0 0 -0.25 0 1 0 0 0 0 0 0 0 -0.5 0 0 0 0 0 13: 0 0 0 -1 0 0 -0.25 -0.25 -1 0 0.25 0 0 4 0 0 0 0.25 0 -1 0 -1 0 0 0 0 14: 0 0 0 0 -1 0.25 0.25 0 0 -1 0 0 0 0 4 0 0 -0.25 -0.25 0 -1 0 -1 0 0 0 15: 0 0 0 0 0 0 0 0 -0.5 0 0 0 0 0 0 1 0 0 0.25 0 0 -0.5 0 0 0 0 16: 0 0 0 0 0 0 0 0.25 0 -0.5 0 0 0 0 0 0 1 0 0 0 0 0 -0.5 0 0 0 17: 0 0 0 0 0 0 0 0 0 0 0 0 0 0.25 -0.25 0 0 1.25e-05 0 -0.25 0 0 0.25 0 0 0 18: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0.25 0 0 1.25e-05 0 0 -0.25 0.25 0 0 0 19: 0 0 0 0 0 0 0 0 0 0 -0.25 -0.5 0 -1 0 0 0 -0.25 0 2 0 0 0 -0.5 0 0 20: 0 0 0 0 0 0 0 0 0 0 0.25 0 -0.5 0 -1 0 0 0 0 0 2 0 0 0 -0.5 -0.25 21: 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 -0.5 0 0 -0.25 0 0 2 0 -0.5 0 0.25 22: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 -0.5 0.25 0.25 0 0 0 2 0 -0.5 0 23: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 0 -0.5 0 1 0 -0.25 24: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 0 -0.5 0 1 0.25 25: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0.25 0 -0.25 0.25 1.25e-05 ``` I’m trying to understand the order of the u1, u2, p variables in this matrix. Because I had thought it would be ordered like [u1\_1, u1\_2, u1\_3, …, u1\_NV, u2\_1, u2\_2, u2\_3, …, u2\_NV, p\_1, p\_2, …, p\_NT] but that’s not the case. here is the matrix when I generated it using this order: ```auto 1 -0.5 0 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.25 0 0 0 0 0 0 0 -0.5 2 -0.5 0 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0 0.25 0 0 0 0 0 0 -0.5 1 0 0 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0 0 0 0 0 -0.5 0 0 2 -1 0 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0.25 0 0 0.25 0 0 0 0 -1 0 -1 4 -1 0 -1 0 0 0 0 0 0 0 0 0 0 0 -0.25 0 0.25 -0.25 0 0.25 0 0 0 -0.5 0 -1 2 0 0 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0 0 -0.25 0 0 0 0 -0.5 0 0 1 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.25 0 0 0 0 0 0 -1 0 -0.5 2 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0 0.25 0 0 0 0 0 -0.5 0 -0.5 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.25 0 0 0 0 0 0 0 0 0 1 -0.5 0 -0.5 0 0 0 0 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 2 -0.5 0 -1 0 0 0 0 0.25 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 1 0 0 -0.5 0 0 0 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 0 0 2 -1 0 -0.5 0 0 0 -0.25 0 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 -1 4 -1 0 -1 0 -0.25 0 0 -0.25 0.25 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 -0.5 0 -1 2 0 0 -0.5 0 0 -0.25 0 0 0 0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 0 0 1 -0.5 0 0 0 0 0 0 -0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 -0.5 2 -0.5 0 0 0 0 -0.25 0 0 -0.25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5 0 -0.5 1 0 0 0 0 0 0 -0.25 0 0.25 -0.25 0 0 0 0 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0.0001 0 0 0 0 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0 0.0001 0 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0.0001 0 0 0 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0 0 0.0001 0 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0.0001 0 0 0 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0 0 0.0001 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0 0.0001 0 0 0 0 0 0 0 0 0.25 -0.25 0 0 0 0 0.25 0 0 -0.25 0 0 0 0 0 0 0 0 0.0001 ``` which is basically a matrix of the form ```auto A 0 Bx.T 0 A By.T Bx By eps*I ``` So my question is where can I find this variable order information of the matrix A or the fespace XhxXhxMh? so I can compare the matrices Thank you very much for your help and have a good day. --- _[View the full topic](https://community.freefem.org/t/order-of-variables-in-matrix-generated-with-varf-with-a-p1-p1-p0-fespace/3489)._