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belson17 / modred

Modred main repository
BSD 2-Clause "Simplified" License
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balanced truncation order issue #25

Closed shaesaert closed 4 years ago

shaesaert commented 7 years ago

There seems to be an error in the balanced_truncation function (modred.util), it does not take orders that are lower than Len(E).

It can be fixed by changing: https://github.com/belson17/modred/blob/c84f67afe03fd1f18fdd7bb99e964c3c11a2040b/modred/util.py#L481

to 

SL = Lo.dot(U[:,:order]).dot(np.diag(E[:order]**-0.5))
SR = Lc.dot(V[:,:order]).dot(np.diag(E[:order]**-0.5))
belson17 commented 7 years ago

Thanks for catching this. I'll create an issue in github and we should have it fixed in the next release. Best, Brandt

On Thu, Oct 12, 2017 at 5:54 PM, shaesaert notifications@github.com wrote:

There seems to be an error in the balanced_truncation function (modred.util), it does not take orders that are lower than Len(E).

It can be fixed by changing: https://github.com/belson17/modred/blob/c84f67afe03fd1f18fdd7bb99e964c 3c11a2040b/modred/util.py#L481

to

SL = Lo.dot(U[:,:order]).dot(np.diag(E[:order]-0.5))SR = Lc.dot(V[:,:order]).dot(np.diag(E[:order]-0.5))

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