Suppose I have an invertable $n \times n$ matrix, $M$, where certain entries are negative. Does there exist another invertible matrix, $P$, which i can multiply with $M$ to obtain a matrix will all positive entries?
And a followup:
Suppose I have some $n \times n$ matrix, $M$, where certain entries are negative. Does there exist another matrix, $P$, which i can multiply with $M$ to obtain a matrix will all positive entries i.e. $PM$ = abs($M$)? In cases where it does exist, how do i find it?