Number of steps in staircase external

[mattberjon]

I don't recall the number of steps and size of steps the staircase method can do. It would be interesting to dig a bit in order to:

• test the code
• ensure its functionalities
• get rid of bugs
• update its documentation (in the code and in the proper documentation)

[mattberjon]

The staircase algorithm work only as one step up and one step down. Any attempt of modifying the step parameters crash the algorithm that won't never converge.