Plotting issue on square mesh

General Discussion
1

Hello,
I just installed the FreeFem++ v4.11 on Linux Mint 20.3 on my new machine.
I was testing the codes in the examples and encountered segfault with plotting on a square mesh.

For example, this code produces segfault when it comes to the plot line:

mesh Th = square(150, 50, [3x, y]);
plot(Th,wait=1);
fespace Vh(Th, P1);
Vh u;
u = cos(2.0pixy);
plot(u,wait=1,cmm=“initial field”);

However, if I set u = const, then there is no segfault.

On the other hand, this code goes through fine:

border C(t=0, 2pi){x=cos(t); y=sin(t);}
mesh Th = buildmesh(C(50));
fespace Vh(Th, P1);
Vh u;
u = cos(2.0pixy);
plot(u,wait=1,cmm=“initial field”);

Any ideas on what could be going wrong?

2

Do you have old version of freefem installed
Check with

which freefem++
which ffglut

If the paths are not the same then you have two version so remote thé old one

3

I only have one version.

4

You can try to create a file of the plot

FreeFem++ script.edp -fglut script.fglut

to see the plot

ffglut  -vvv script.fglut

And the have an idea of the problem!

5

Thank you for your suggestion. I tried what you said and here is what I’m getting. If I use

mesh Th = square(15,15);

then ffglut plots it without an issue. But with

mesh Th = square(20,20);

I get the following error message:
out.pdf (76.3 KB)

6

Can you sent the file script.fglut ?

7

Here it is:
fflgut file

8

I have try the glut file is ok for my version of FreeFem

the output is :

MBP-M1-FH:Downloads hecht$ ffglut -v Heat1.fglut 
 glutscreenscale 1 1152 744 1728 1117
ffglut : 10
 fopen :Heat1.fglut 0x1ee0c4d50
 mode read = r
 GRead : nv 441 800 80
  -- End of read: mesure = 1 border mesure 4
  -- BuildAdj:0x600000618e60 nb Elememt 800 nb vertices 441
             : nb adj  = 1240 on border 80 nea = 3 nva = 2 nb no manifold border 0

  -- Mesh2  (File *), d 2, n Tet 800, n Vtx 441 n Bord 80



 next is build 0x13ee0efa0 wait :1 -> 1 gwait = 0



on a lue le premier plot next plot: 0x13ee0efa0
pView 0 0 1153 745 kscreenscale=  1
DefaultView 2 0 theplot 0x0
 change current plot to: 0x13ee0efa0 et  Lock Plot . winnum  0
OneWindow:: add 0 -> 0
OneWindow:: set 0 -> 0
DefaultView 2 0 theplot 0x13ee0efa0
 We Read a plot  : 1 0x0 -1
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 01
DefaultView 0 0 theplot 0x13ee0efa0
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
Key winnum:  0
 send signal For Next plot, skip: No More Plot !  
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
Key winnum:  0
 send signal For Next plot, skip: No More Plot !  
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
Key winnum:  0
 send signal For Next plot, skip: No More Plot !  
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
      ThePlot::Plot 1 0x13ee0efa0 win 0x13ef60170 11
Key winnum:  0
MBP-M1-FH:Downloads hecht$

The only way is to recompile ffglut and reinstall.

remove ffglut

MBP-M1-FH:~ hecht$ cd ff/ff-10/
MBP-M1-FH:ff-10 hecht$ rm src/nw/ffglut 
make 

/Library/Developer/CommandLineTools/usr/bin/make  all-am
make[4]: Nothing to be done for `all-am'.
Making all in nw
g++  -Wno-undefined-var-template -m64 -fPIC -DNDEBUG -O3 -O3 -O3 -std=c++14 -DBAMG_LONG_LONG  -DNCHECKPTR  -fPIC   -o ffglut ../femlib/Drawing.o ../femlib/fem.o ../fflib/ffapi.o ../femlib/FQuadTree.o ../femlib/GQuadTree.o ../femlib/Mesh1dn.o ../femlib/Mesh2dn.o ../femlib/Mesh3dn.o ../femlib/MeshSn.o ../femlib/MeshLn.o ../femlib/mshptg.o ../Graphics/ffglut.o ../Graphics/ffthreads.o ../Graphics/gggg.o ../libMesh/libMesh.a -framework GLUT -framework OpenGL -framework Cocoa -lpthread 
Making all in mpi
make[3]: Nothing to be done for `all'.
make install
9

I reinstalled Linux 20.2 and then everything worked.
Thank you for your help!

10

Very good, I close this plotting issue.