evaluate v = p/sqrt(a²+(a²-b²)-sqrt(a²(sqrt(b²-y²)a/b+sqrt(a²-b²))²/((sqrt(b²-y²)a/b)²+y²+(a²-b²)+sqrt(a²-b²)2(sqrt(b²-y²))a/b))2(sqrt(a²-b²))) where a=b