All Questions

Suppose a matrix equation $Ax = b$ has no solution ($b$ is not in the column space of $A$) How can I find a vector $x^\prime$ so that $Ax^\prime$ is the closest possible vector to $b$?

For any real matrix $B\in\mathbb{R}^{n\times n},n\ge 2$ and precision $\varepsilon$, is there a real matrix $A\in\mathbb{R}^{n\times n}$ such that $\|e^A-B\|_F<\varepsilon$? ($F$ refers to ...