What is calculus 4?

As an AI language model, I don't have information about specific courses that are given in specific institutions or countries. In general, Calculus 4 is an advanced course in calculus, building on the material covered in earlier calculus courses (Calculus 1, 2, and 3). Topics in Calculus 4 typically include multivariable calculus, vector calculus, differential equations, and possibly complex variables. The course is usually taken by students majoring in engineering, mathematics, and other technical fields. It is important to note that the contents of Calculus 4 may vary from one institution to another.