Consider the *m × n* system of linear equations

$$\mathbf{Ax=b}$$ | (35) |

If *m = n* and **A** is not singular,
Equation 35
possesses a unique solution and is referred to as a fully
determined system of equations. When *m > n* (or
*m = n* and **A** is singular),
Equation 35
is an underdetermined system of equations. Otherwise,
*m < n* and
Equation 35
is overdetermined system of equations.