Add correct handling of NaN in product_human and ratio_human.
Add correct handling of NaN in product_human and ratio_human.

ripple/ripple-lib,ripple/ripple-lib,darkdarkdragon/ripple-lib,ripple/ripple-lib,ripple/ripple-lib,darkdarkdragon/ripple-lib,wilsonianb/ripple-lib,darkdarkdragon/ripple-lib,wilsonianb/ripple-lib,wilsonianb/ripple-lib