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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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