example updated with check of second derivative
example updated with check of second derivative

PaddySchmidt/gosl,cpmech/gosl,cpmech/gosl,cpmech/gosl,PaddySchmidt/gosl,cpmech/gosl,PaddySchmidt/gosl,PaddySchmidt/gosl,PaddySchmidt/gosl,PaddySchmidt/gosl,cpmech/gosl