Approximation of an Exponential Correlation Matrix with a Constant Correlation Matrix

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I am given with a $N times N$ matrix



$$
beginalign*
A =
beginbmatrix
1 & rho_h & ldots & rho_h^N - 1 \
rho_h & 1 & ldots & rho_h^N - 2 \
vdots & vdots & ddots & vdots \
rho_h^N - 1 & rho_h^N - 2 & ldots & 1
endbmatrix,
endalign*
$$



where $0 leq rho_h leq 1$ and $N geq 2$. I would like to approimate A with another $N times N$ matrix given as:



$$
B= beginbmatrix
1 & rho & ldots & rho \
rho & 1 & ldots & rho \
vdots & vdots & ddots & vdots \
rho & rho & ldots & 1
endbmatrix.
$$



This basically means, finding a relation between $rho$ and $rho_h$ such that $A approx B$.



Any thoughts on, how can this be achieved?










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  • Do you want a 1 in the lower right corners?
    – AlgebraicsAnonymous
    Sep 4 at 5:51










  • Yes... made correction. Thanks!
    – Kamal K Garg
    Sep 4 at 8:36














up vote
0
down vote

favorite












I am given with a $N times N$ matrix



$$
beginalign*
A =
beginbmatrix
1 & rho_h & ldots & rho_h^N - 1 \
rho_h & 1 & ldots & rho_h^N - 2 \
vdots & vdots & ddots & vdots \
rho_h^N - 1 & rho_h^N - 2 & ldots & 1
endbmatrix,
endalign*
$$



where $0 leq rho_h leq 1$ and $N geq 2$. I would like to approimate A with another $N times N$ matrix given as:



$$
B= beginbmatrix
1 & rho & ldots & rho \
rho & 1 & ldots & rho \
vdots & vdots & ddots & vdots \
rho & rho & ldots & 1
endbmatrix.
$$



This basically means, finding a relation between $rho$ and $rho_h$ such that $A approx B$.



Any thoughts on, how can this be achieved?










share|cite|improve this question























  • Do you want a 1 in the lower right corners?
    – AlgebraicsAnonymous
    Sep 4 at 5:51










  • Yes... made correction. Thanks!
    – Kamal K Garg
    Sep 4 at 8:36












up vote
0
down vote

favorite









up vote
0
down vote

favorite











I am given with a $N times N$ matrix



$$
beginalign*
A =
beginbmatrix
1 & rho_h & ldots & rho_h^N - 1 \
rho_h & 1 & ldots & rho_h^N - 2 \
vdots & vdots & ddots & vdots \
rho_h^N - 1 & rho_h^N - 2 & ldots & 1
endbmatrix,
endalign*
$$



where $0 leq rho_h leq 1$ and $N geq 2$. I would like to approimate A with another $N times N$ matrix given as:



$$
B= beginbmatrix
1 & rho & ldots & rho \
rho & 1 & ldots & rho \
vdots & vdots & ddots & vdots \
rho & rho & ldots & 1
endbmatrix.
$$



This basically means, finding a relation between $rho$ and $rho_h$ such that $A approx B$.



Any thoughts on, how can this be achieved?










share|cite|improve this question















I am given with a $N times N$ matrix



$$
beginalign*
A =
beginbmatrix
1 & rho_h & ldots & rho_h^N - 1 \
rho_h & 1 & ldots & rho_h^N - 2 \
vdots & vdots & ddots & vdots \
rho_h^N - 1 & rho_h^N - 2 & ldots & 1
endbmatrix,
endalign*
$$



where $0 leq rho_h leq 1$ and $N geq 2$. I would like to approimate A with another $N times N$ matrix given as:



$$
B= beginbmatrix
1 & rho & ldots & rho \
rho & 1 & ldots & rho \
vdots & vdots & ddots & vdots \
rho & rho & ldots & 1
endbmatrix.
$$



This basically means, finding a relation between $rho$ and $rho_h$ such that $A approx B$.



Any thoughts on, how can this be achieved?







linear-algebra matrices approximation






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edited Sep 4 at 8:41

























asked Sep 4 at 5:35









Kamal K Garg

12




12











  • Do you want a 1 in the lower right corners?
    – AlgebraicsAnonymous
    Sep 4 at 5:51










  • Yes... made correction. Thanks!
    – Kamal K Garg
    Sep 4 at 8:36
















  • Do you want a 1 in the lower right corners?
    – AlgebraicsAnonymous
    Sep 4 at 5:51










  • Yes... made correction. Thanks!
    – Kamal K Garg
    Sep 4 at 8:36















Do you want a 1 in the lower right corners?
– AlgebraicsAnonymous
Sep 4 at 5:51




Do you want a 1 in the lower right corners?
– AlgebraicsAnonymous
Sep 4 at 5:51












Yes... made correction. Thanks!
– Kamal K Garg
Sep 4 at 8:36




Yes... made correction. Thanks!
– Kamal K Garg
Sep 4 at 8:36










1 Answer
1






active

oldest

votes

















up vote
0
down vote













You might want to use the least squares method, that is, to find a $rho in [0,1]$ that minimizes
$$
sum_k=1^N 2sum_j=1^k-1 (rho - rho_h^j)^2;
$$
note that the sum sums for each $k$ a boomerang-shaped or edge-shaped part of the matrix that is basically a rectangle that starts in $c_N,k$, goes to $c_k,k$ and makes an edge there and continues to $c_k,N$, where $c_k,k$ is left out, where $C$ is an arbitrary matrix.



Moreover, whenever $| cdot |$ is a matrix norm (submultiplicative or not), you can think about minimizing $|A - B|$ as a function of $rho$. In the above example, the norm was just the Euclidean norm on $mathbb R^n^2$.






share|cite|improve this answer




















  • The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
    – Kamal K Garg
    Sep 5 at 2:50











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
0
down vote













You might want to use the least squares method, that is, to find a $rho in [0,1]$ that minimizes
$$
sum_k=1^N 2sum_j=1^k-1 (rho - rho_h^j)^2;
$$
note that the sum sums for each $k$ a boomerang-shaped or edge-shaped part of the matrix that is basically a rectangle that starts in $c_N,k$, goes to $c_k,k$ and makes an edge there and continues to $c_k,N$, where $c_k,k$ is left out, where $C$ is an arbitrary matrix.



Moreover, whenever $| cdot |$ is a matrix norm (submultiplicative or not), you can think about minimizing $|A - B|$ as a function of $rho$. In the above example, the norm was just the Euclidean norm on $mathbb R^n^2$.






share|cite|improve this answer




















  • The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
    – Kamal K Garg
    Sep 5 at 2:50















up vote
0
down vote













You might want to use the least squares method, that is, to find a $rho in [0,1]$ that minimizes
$$
sum_k=1^N 2sum_j=1^k-1 (rho - rho_h^j)^2;
$$
note that the sum sums for each $k$ a boomerang-shaped or edge-shaped part of the matrix that is basically a rectangle that starts in $c_N,k$, goes to $c_k,k$ and makes an edge there and continues to $c_k,N$, where $c_k,k$ is left out, where $C$ is an arbitrary matrix.



Moreover, whenever $| cdot |$ is a matrix norm (submultiplicative or not), you can think about minimizing $|A - B|$ as a function of $rho$. In the above example, the norm was just the Euclidean norm on $mathbb R^n^2$.






share|cite|improve this answer




















  • The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
    – Kamal K Garg
    Sep 5 at 2:50













up vote
0
down vote










up vote
0
down vote









You might want to use the least squares method, that is, to find a $rho in [0,1]$ that minimizes
$$
sum_k=1^N 2sum_j=1^k-1 (rho - rho_h^j)^2;
$$
note that the sum sums for each $k$ a boomerang-shaped or edge-shaped part of the matrix that is basically a rectangle that starts in $c_N,k$, goes to $c_k,k$ and makes an edge there and continues to $c_k,N$, where $c_k,k$ is left out, where $C$ is an arbitrary matrix.



Moreover, whenever $| cdot |$ is a matrix norm (submultiplicative or not), you can think about minimizing $|A - B|$ as a function of $rho$. In the above example, the norm was just the Euclidean norm on $mathbb R^n^2$.






share|cite|improve this answer












You might want to use the least squares method, that is, to find a $rho in [0,1]$ that minimizes
$$
sum_k=1^N 2sum_j=1^k-1 (rho - rho_h^j)^2;
$$
note that the sum sums for each $k$ a boomerang-shaped or edge-shaped part of the matrix that is basically a rectangle that starts in $c_N,k$, goes to $c_k,k$ and makes an edge there and continues to $c_k,N$, where $c_k,k$ is left out, where $C$ is an arbitrary matrix.



Moreover, whenever $| cdot |$ is a matrix norm (submultiplicative or not), you can think about minimizing $|A - B|$ as a function of $rho$. In the above example, the norm was just the Euclidean norm on $mathbb R^n^2$.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Sep 4 at 5:58









AlgebraicsAnonymous

1,04512




1,04512











  • The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
    – Kamal K Garg
    Sep 5 at 2:50

















  • The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
    – Kamal K Garg
    Sep 5 at 2:50
















The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
– Kamal K Garg
Sep 5 at 2:50





The similar problem is addressed in link. The snapshot from the paper is available at link. The paper used the technique presented in [17, Section IV] which is available at link. Just wondering, whether the approach you offered is different from or similar to this. Can you please have a look at the links and advise?
– Kamal K Garg
Sep 5 at 2:50


















 

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