General non-algebraic solution to finding a point on the line of the intersection of two planes.

I am having trouble implementing this algorithm:

1/ Given planes pl and p2, compute line L = p+t*d of their intersection. // Return 0 if no such line exists int IntersectPlanes (Plane p1, Plane p2, Point &p, Vector &d) { // Compute direction of intersection line d = Cross (p1.n, p2.n); // If d is (near) zero, the planes are parallel (and separated) // or coincident, so they're not considered intersecting float denom - Dot(d, d); if (denom