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Convert a Hermitian-definite matrix pencil into a matrix with the same eigenvalues
ResourceFunction["DefinitePencilReduce"][{m,a}] yields a list of matrices {s,t}, where s is a Hermitian matrix with the same eigenvalues as the Hermitian definite matrix pencil {m,a}, and t is a transformation matrix that transforms the eigenvectors of s into the eigenvectors of {m,a}. |
A symmetric definite pencil:
| In[1]:= |
Reduce the pencil:
| In[2]:= |
| Out[2]= |
Compute the eigenvalues of the transformed matrix:
| In[3]:= |
| Out[3]= | ![]() |
These are the same as the eigenvalues of the original pencil:
| In[4]:= |
| Out[4]= | ![]() |
Compute the normalized eigenvectors of the transformed matrix:
| In[5]:= |
| Out[5]= | ![]() |
These are the same as the eigenvectors of the original pencil, up to a normalization constant:
| In[6]:= |
| Out[6]= | ![]() |
A machine precision symmetric definite pencil:
| In[7]:= |
Reduce the pencil:
| In[8]:= |
| Out[8]= |
Compute the eigenvalues of the transformed matrix:
| In[9]:= |
| Out[9]= |
These are the same as the eigenvalues of the original pencil:
| In[10]:= |
| Out[10]= |
Compute the normalized eigenvectors of the transformed matrix:
| In[11]:= |
| Out[11]= |
These are the same as the eigenvectors of the original pencil, up to a normalization constant:
| In[12]:= |
| Out[12]= |
Reduce an exact symmetric definite pencil:
| In[13]:= | ![]() |
| Out[13]= | ![]() |
Reduce a symmetric definite pencil with 24-digit precision arithmetic::
| In[14]:= | ![]() |
| Out[14]= | ![]() |
A random symmetric definite pencil:
| In[15]:= |
| Out[15]= | ![]() |
Reduce the pencil:
| In[16]:= |
| Out[16]= | ![]() |
A random Hermitian definite pencil:
| In[17]:= |
| Out[17]= | ![]() |
Reduce the pencil:
| In[18]:= |
| Out[18]= | ![]() |
Use the "Cholesky" method to reduce the definite pencil:
| In[19]:= |
| Out[19]= |
Use the "Eigensystem" method to reduce the definite pencil:
| In[20]:= |
| Out[20]= |
A definite pencil:
| In[21]:= | ![]() |
Reduce the definite pencil:
| In[22]:= |
| Out[22]= |
Verify that m is given by ConjugateTranspose[t].s.t:
| In[23]:= |
| Out[23]= |
Verify that a is given by ConjugateTranspose[t].t:
| In[24]:= |
| Out[24]= |
DefinitePencilReduce is left unevaluated if the argument is not a definite pencil:
| In[25]:= | ![]() |
| Out[25]= |
| In[26]:= | ![]() |
| Out[26]= |
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