percusse
• Member for 5 years, 4 months
• Last seen more than 3 years ago
• Amsterdam, Netherlands

Took me quite a while to figure this out and as usual it becomes obvious after you find the culprit. After checking the problematic cases reported in David S. Watkins. A case where balancing is ...

Late answer but the matrix can be thought of the following sum of rank-$2$ matrices which allows for having smaller block sizes as the number of blocks increase. \begin{align*} c_{20}=\left( \... View answer 4 votes Well, other than the usual "don't invert your matrices unless you need the inverse itself" you can still use the banded routines ?gbtrf and then use ?gbtrs with the right hand side being an identity ... View answer 1 votes That equivalence is only valid if A is invertible, hence it is a result but not a definition. This is typically done via the following relation \exp\left(\begin{bmatrix}A & B\\0 &0\end{...

No this is not possible. And actually, it is a good practice to not to rely on this type of inferences. Well before anything they tend to get in the way and certain operations are not structure ...

If this is the only relevant part of your problem, you can write this as a semidefinite program. Since $x_1, x_2$ do not appear individually you can treat it as a square of a positive number then your ...