# Help with Plasticity formula.

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Hello,

I am trying to implement the techniques used in this paper

I have a problem understanding a couple of formula representations.

First.   <- what does that arrow stand for?

does taht has something to do with the output of that equation? that the output should be the same type/structure as S(matrix) ?

Second.   ||S-I||2(lowercase) .

S and I are both matricies.3x3

as i understand from wiki... ||...|| just needs to match the number to the closest integer number, so i guess that should be easy.

but i also found another explanation, that ||...|| is a matrix representation.

and the last question is what does that number 2, does after the ||....|| part?

This forum has been very helpful for the past week, instant responses,  hope to get some more help .

Thanks A Lot !

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That arrow is usually used when describing algorithms and represents an assignment, an update of the variable the arrow points to. ||Sp - I||2 is the spectral norm of the matrix Sp - I. The spectral norm of a matrix A is the square root of the maximum eigenvalue of AHA where AH is the conjugate transpose of A (the transpose if the matrix is real).

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If you are implementing that paper, you might be interested in: http://www.matthiasmueller.info/realtimephysics/.

And, when it comes to Shape Matching, there is code available at http://www.matthiasmueller.info/demos/index.htm.

Hope that helps!

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