[EDF22126] : eigen values with identity matrix

diff --git a/src/INTERP_KERNEL/GenMathFormulae.hxx b/src/INTERP_KERNEL/GenMathFormulae.hxx
index 19bc41024cee418eae75bc663769965b7d117577..037f96cfeb2de3c44eb982493e3620b4e0c6e5af 100644 (file)
--- a/src/INTERP_KERNEL/GenMathFormulae.hxx
+++ b/src/INTERP_KERNEL/GenMathFormulae.hxx
@@ -32,6 +32,8 @@ namespace INTERP_KERNEL
    * matrix[0]=m_xx, matrix[1]=m_yy, matrix[2]=m_zz,
    * matrix[3]=m_xy, matrix[4]=m_yz, matrix[5]=m_xz
    * This method returns the 3 eigenvalues in 'eigenVals'.
+   * 
+   * https://en.wikipedia.org/wiki/Eigenvalue_algorithm
    */
   void computeEigenValues6(const double *matrix, double *eigenVals)
   {
@@ -44,7 +46,10 @@ namespace INTERP_KERNEL
     double tmp=p*sqp;
     double phi;
     if(fabs(q)<=fabs(tmp))
-      phi=1./3.*acos(q/tmp);
+      if(tmp !=0)
+        phi=1./3.*acos(q/tmp);
+      else // EDF22176
+        phi=1./3.;
     else
       phi=0.;
     if(phi<0.)

diff --git a/src/MEDCoupling_Swig/MEDCouplingBasicsTest7.py b/src/MEDCoupling_Swig/MEDCouplingBasicsTest7.py
index 3e480e24b80036868bde0a1332f034d5976b3aed..d279d1b2cbcc50ae2eccc570a5b89f597f5a33a0 100644 (file)
--- a/src/MEDCoupling_Swig/MEDCouplingBasicsTest7.py
+++ b/src/MEDCoupling_Swig/MEDCouplingBasicsTest7.py
@@ -897,6 +897,19 @@ class MEDCouplingBasicsTest7(unittest.TestCase):
         f.setArray(DataArrayDouble(18*[0.]))
         self.assertTrue(f.getLocalizationOfDiscr().isEqual(coo[conn],1e-10))
 
+    def testDADEigenValuesPb(self):
+        """EDF22126 : eigen values with Identity matrix returned nan. Now it returns correct eigen values 1.0 """
+        valuesExp = DataArrayDouble([(1.,1.,1.),(2.,-1.,0.),(2.,0.,1.),(3.,0.,0.)])
+        d = DataArrayDouble(4, 6)
+        for i,(v0, v1, v2, v3, v4, v5,) in enumerate([
+                (1, 1, 1, 0, 0, 0),
+                (1, 0, 0, 1, 0, 1),
+                (1, 1, 1, 0, 1, 0),
+                (1, 1, 1, 1, 1, 1)]):
+            d[i] = [v0, v1, v2, v3, v4, v5]
+        self.assertTrue(d.eigenValues().isEqual(valuesExp,1e-12))
+        pass
+
     pass
 
 if __name__ == '__main__':