The Joy of Mathematics

Title: Astroid, Attempt 1
Description: x = cos(q) + cos(3q); y = sin(q) + sin(3q)
Equation: z = (4x³/r³ - 2x/r - x) * (4y/r - 4y³/r³ - y)
Drawing Limits: (-2, -2) - (2, 2)
Min z: -1.69749, Max z: 1.69734