w many iterations to allow (default: 100)
        opts.maxTotalIts    How many iterations to allow, including linesearch iterations
                        (default: 5000)
        opts.printEvery     How often to display information (default: 1)
        opts.errFcn         A function handle (or cell array of several function handles)
                        that computes whatever you want. The output will be printed
                        to the screen every 'printEvery' iterations. (default: [] )
        