Backpropagation proximal gradient
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mblum94 commented
Dear @khammernik ,
I've got a question/comment concerning back propagation of the proximal gradient layer with respect to lambda.
I got curious, reading your current MRM paper where you wrote that training becomes unstable when lambda is not fixed.
Following your conventions,
M := lambda A^HA + 1
Q := M^-1.
Now, the the derivative of the inverse of a matrix (with respect to lambda) is given by:
Q'=-Q M' Q
In the code, I see twice the Q as expected but not M' = A^HA.
Is it missing or does it cancel somehow?
Best regards,
Moritz