The Wronskian of a differential equation of the form y'' + p(t)y' + q(t)y = 0 is:
where y1 and y2 are solutions of the said equation.
If the Wronskian is nonzero, it means y1 and y2 make up a fundamental set of solutions for the equation.
Relation to Linear Algebra
Recall from linear algebra that, if the determinant of a matrix is nonzero, it means that the two columns of the matrix are linearly independent of each other. Thus, a nonzero Wronskian shows that the solutions y1 and y2 are linearly independent, or make up a fundamental set of solutions.
An alternate expression for the Wronskian (found by algebraic manipulation and similar processes):