The function box will accept any input that is a valid equation. Letters (aside from x,y,z, and r) are variables that can be adjusted using the boxes on the side. You can use the following in an equation:

• x, y, and z
• r (= sqrt(x² + y²)
• rho, theta, and phi

In addition, most trig functions are available, including sin, arctan, and cosh (hyperbolic cos). Some other functions, such as round, floor, and mod are also allowed.