[Linear Algebra] Rectangular Matrix

Rectangular Matrix $A$ in $A\textbf{x} = \textbf{b}$

• $A \in \mathbb{R}^{m \times n}$
  • m : number of equations
  • n : number of variables
• if m < n : more variables than equations
  • usually infinitely many solutions exist (under-determined system)
• if m > n : more equations than variables
  • usually no solution exist (over-determined system)