Cholesky decomposition of normalized matrix

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I need to compute the Cholesky decomposition $A=LL^T$ in order to obtain the matrix $L$.



My matrix $A$ is often badly conditioned (non-positive definite). I am now trying an approach where I normalize $A$ with a matrix $N$ before performing the decomposition. I want to reapply $N$ to the obtained result in order to find the correct matrix $L$.



Is such a method possible, and if so, how and why would it work? Are there any alternative ways to deal with non-positive definite matrices in a Cholesky decomposition?










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  • If the non psd-ness stems only from numerical imprecision, you could simply stop the Cholesky process when the square root of a very slightly negative number occurs. At that point you have an approximate partial, low rank decomposition, which might be good enough for your purposes.
    – kimchi lover
    Sep 3 at 13:03














up vote
0
down vote

favorite












I need to compute the Cholesky decomposition $A=LL^T$ in order to obtain the matrix $L$.



My matrix $A$ is often badly conditioned (non-positive definite). I am now trying an approach where I normalize $A$ with a matrix $N$ before performing the decomposition. I want to reapply $N$ to the obtained result in order to find the correct matrix $L$.



Is such a method possible, and if so, how and why would it work? Are there any alternative ways to deal with non-positive definite matrices in a Cholesky decomposition?










share|cite|improve this question





















  • If the non psd-ness stems only from numerical imprecision, you could simply stop the Cholesky process when the square root of a very slightly negative number occurs. At that point you have an approximate partial, low rank decomposition, which might be good enough for your purposes.
    – kimchi lover
    Sep 3 at 13:03












up vote
0
down vote

favorite









up vote
0
down vote

favorite











I need to compute the Cholesky decomposition $A=LL^T$ in order to obtain the matrix $L$.



My matrix $A$ is often badly conditioned (non-positive definite). I am now trying an approach where I normalize $A$ with a matrix $N$ before performing the decomposition. I want to reapply $N$ to the obtained result in order to find the correct matrix $L$.



Is such a method possible, and if so, how and why would it work? Are there any alternative ways to deal with non-positive definite matrices in a Cholesky decomposition?










share|cite|improve this question













I need to compute the Cholesky decomposition $A=LL^T$ in order to obtain the matrix $L$.



My matrix $A$ is often badly conditioned (non-positive definite). I am now trying an approach where I normalize $A$ with a matrix $N$ before performing the decomposition. I want to reapply $N$ to the obtained result in order to find the correct matrix $L$.



Is such a method possible, and if so, how and why would it work? Are there any alternative ways to deal with non-positive definite matrices in a Cholesky decomposition?







matrix-decomposition positive-definite






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asked Sep 3 at 7:50









Michiel

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  • If the non psd-ness stems only from numerical imprecision, you could simply stop the Cholesky process when the square root of a very slightly negative number occurs. At that point you have an approximate partial, low rank decomposition, which might be good enough for your purposes.
    – kimchi lover
    Sep 3 at 13:03
















  • If the non psd-ness stems only from numerical imprecision, you could simply stop the Cholesky process when the square root of a very slightly negative number occurs. At that point you have an approximate partial, low rank decomposition, which might be good enough for your purposes.
    – kimchi lover
    Sep 3 at 13:03















If the non psd-ness stems only from numerical imprecision, you could simply stop the Cholesky process when the square root of a very slightly negative number occurs. At that point you have an approximate partial, low rank decomposition, which might be good enough for your purposes.
– kimchi lover
Sep 3 at 13:03




If the non psd-ness stems only from numerical imprecision, you could simply stop the Cholesky process when the square root of a very slightly negative number occurs. At that point you have an approximate partial, low rank decomposition, which might be good enough for your purposes.
– kimchi lover
Sep 3 at 13:03















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