> a = 10, b = 28, c = 6,
```
def lorenz_IV(a, b, c):
return lambda x, y, z:(
(-a*x*x*x + (2*a + b - z)*x*x*y + (a - 2)*x*y*y + (z - b)*y*y*y)/(2*(x*x + y*y)),
((b - z)*x*x*x + (a - 2)*x*x*y + (-2*a - b + z)*x*y*y- a*y*y*y)/(2*(x*x + y*y)),
2*x*x*x*y - 2*x*y*y*y - c*z
)
```
## References
> Lorenz-Attraktor
> http://page.math.tu-berlin.de/~gunn/Files/mvws13html/html2420/lorenz2420.html
>
> R. Miranda & E. Stone, The proto-Lorenz system, Physics Letters A 178 (1993) 105-113.