gonum/optimize — pull request #16 by vladimir-ch (2014-12-05 00:54:30+00:00)
Title: Improve QuadraticStepSize

* Use previous step size in case interpolation is not done
* Use floats.EqualWithinRel rather than own comparison
* Use interpolation only if there is a chance of interpolating the
function well by a quadratic
* Remove MinStepSize, it is not necessary that users manipulate it