# Rosenbrock function

### From Glossary

The original form has 2 variables:

The significance of this function is that it has "bannana-shaped" contours, making it difficult for nonlinear programming algorithms, particularly Cauchy's steepest descent, to solve it. The (global) minimum is at
with
There are variations that extend Rosenbrock's function, many by Schittkowski, such as the following on