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Verify that input metric has strictly positive eigenvalues #320

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Verify that input metric has strictly positive eigenvalues #320

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3bd5e54
added check of positive eigenvalues of input metric in 2D
corentin-prigent Jan 20, 2026
3c0e183
added check of positive eigenvalues of input metric in 3d and S
corentin-prigent Jan 20, 2026
91f792b
correction of size check
corentin-prigent Jan 21, 2026
60bd5da
correction of size check in mmgs
corentin-prigent Jan 21, 2026
922097c
Merge branch 'develop' into feature/negative-eigenvalue
corentin-prigent Jan 21, 2026
66da499
Merge branch 'develop' into feature/negative-eigenvalue
corentin-prigent Jan 21, 2026
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33 changes: 33 additions & 0 deletions src/mmg2d/inout_2d.c
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Original file line number Diff line number Diff line change
Expand Up @@ -978,6 +978,21 @@ int MMG2D_loadSol(MMG5_pMesh mesh,MMG5_pSol sol,const char *filename) {

fclose(inm);

/* For anisotropic metric, check that eigenvalues are stricly positive*/
if ( sol->size == 3 ) {
for (k=1; k<=sol->np; k++) {
double lambda[2],vp[2][2];
MMG5_eigensym(sol->m+3*k,lambda,vp);

if (!(lambda[0] > 0. && lambda[1] > 0.)) {
fprintf(stderr, " ## Error: At least one negative eigenvalue in"
" provided metric file : %lf %lf \n", lambda[0],
lambda[1]);
return -1;
}
}
}

/* stats */
MMG5_printMetStats(mesh,sol);

Expand Down Expand Up @@ -1092,6 +1107,24 @@ int MMG2D_loadAllSols(MMG5_pMesh mesh,MMG5_pSol *sol, const char *filename) {
}
fclose(inm);

/* For anisotropic metric, check that eigenvalues are stricly positive*/
for ( j=0; j<nsols; j++ ) {
psl = *sol+j;
if ( psl->size == 3 ) {
for ( k=1; k<=psl->np; k++ ) {
double lambda[2],vp[2][2];
MMG5_eigensym(psl->m+3*k,lambda,vp);

if (!(lambda[0] > 0. && lambda[1] > 0.)) {
fprintf(stderr, " ## Error: At least one negative eigenvalue in"
" provided metric file : %lf %lf \n", lambda[0],
lambda[1]);
return -1;
}
}
}
}

/* stats */
MMG5_printSolStats(mesh,sol);

Expand Down
33 changes: 33 additions & 0 deletions src/mmg3d/inout_3d.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2207,6 +2207,21 @@ int MMG3D_loadSol(MMG5_pMesh mesh,MMG5_pSol met, const char *filename) {

fclose(inm);

/* For anisotropic metric, check that eigenvalues are stricly positive*/
if ( met->size == 6 ) {
for (k=1; k<=met->np; k++) {
double lambda[3],vp[3][3];
MMG5_eigenv3d(1,met->m+6*k,lambda,vp);

if (!(lambda[0] > 0. && lambda[1] > 0. && lambda[2] > 0.)) {
fprintf(stderr, " ## Error: At least one negative eigenvalue in"
" provided metric file : %lf %lf %lf \n", lambda[0],
lambda[1], lambda[2]);
return -1;
}
}
}

/* stats */
MMG5_printMetStats(mesh,met);

Expand Down Expand Up @@ -2305,6 +2320,24 @@ int MMG3D_loadAllSols(MMG5_pMesh mesh,MMG5_pSol *sol, const char *filename) {
}
fclose(inm);

/* For anisotropic metric, check that eigenvalues are stricly positive*/
for ( j=0; j<nsols; j++) {
psl = *sol + j;
if ( psl->size == 6 ) {
for (k=1; k<=psl->np; k++) {
double lambda[3],vp[3][3];
MMG5_eigenv3d(1,psl->m+6*k,lambda,vp);

if (!(lambda[0] > 0. && lambda[1] > 0. && lambda[2] > 0.)) {
fprintf(stderr, " ## Error: At least one negative eigenvalue in"
" provided metric file : %lf %lf %lf \n", lambda[0],
lambda[1], lambda[2]);
return -1;
}
}
}
}

/* stats */
MMG5_printSolStats(mesh,sol);

Expand Down
33 changes: 33 additions & 0 deletions src/mmgs/inout_s.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1378,6 +1378,21 @@ int MMGS_loadSol(MMG5_pMesh mesh,MMG5_pSol met,const char* filename) {

fclose(inm);

/* For anisotropic metric, check that eigenvalues are stricly positive*/
if ( met->size == 6 ) {
for (k=1; k<=met->np; k++) {
double lambda[3],vp[3][3];
MMG5_eigenv3d(1,met->m+6*k,lambda,vp);

if (!(lambda[0] > 0. && lambda[1] > 0. && lambda[2] > 0.)) {
fprintf(stderr, " ## Error: At least one negative eigenvalue in"
" provided metric file : %lf %lf %lf \n", lambda[0],
lambda[1], lambda[2]);
return -1;
}
}
}

/* stats */
MMG5_printMetStats(mesh,met);

Expand Down Expand Up @@ -1474,6 +1489,24 @@ int MMGS_loadAllSols(MMG5_pMesh mesh,MMG5_pSol *sol, const char *filename) {
}
fclose(inm);

/* For anisotropic metric, check that eigenvalues are stricly positive*/
for ( j=0; j<nsols; j++) {
psl = *sol + j;
if ( psl->size == 6 ) {
for (k=1; k<=psl->np; k++) {
double lambda[3],vp[3][3];
MMG5_eigenv3d(1,psl->m+6*k,lambda,vp);

if (!(lambda[0] > 0. && lambda[1] > 0. && lambda[2] > 0.)) {
fprintf(stderr, " ## Error: At least one negative eigenvalue in"
" provided metric file : %lf %lf %lf \n", lambda[0],
lambda[1], lambda[2]);
return -1;
}
}
}
}

/* stats */
MMG5_printSolStats(mesh,sol);

Expand Down