bumbar
Newbie level 1
Can somebody help me with this problem
Does some function behaves like this:
\[f(D\cdot f(Dx))=f(D^2\cdot x)\]
Where \[D\] is a Matrix with elements \[d_{ij}\geq 0 \] ,
\[x\] is a vector with elements +1 or -1, and
\[f(\cdot)\] is a function
As you can see if \[f
=y\] then the equation above is true.
But is there some other function then that one, for example does
\[sign\] makes the equation true, where \[sign(\cdot)\]
is the signum function
Does some function behaves like this:
\[f(D\cdot f(Dx))=f(D^2\cdot x)\]
Where \[D\] is a Matrix with elements \[d_{ij}\geq 0 \] ,
\[x\] is a vector with elements +1 or -1, and
\[f(\cdot)\] is a function
As you can see if \[f
=y\] then the equation above is true.But is there some other function then that one, for example does
\[sign
\] makes the equation true, where \[sign(\cdot)\]is the signum function