The InfiniteOpt does't work when deriv(x[i], t) .== -gradf(x[i]) in R^d (d>=2) which is vector defined by user's function gradf.

The InfiniteOpt does't work when deriv(x[i], t) .== -gradf(x[i]) in R^d (d>=2) which is vector defined by user's function gradf. #9916