Return or set lvalue attribute
lvalue(x, ...)# S3 method for default
lvalue(x, ...)
lvalue(x, ...) <- value
# S3 method for default
lvalue(x, ...) <- value
any R object
additional paramters
new loss value to set
attr(x,"lvalue")
lvalue attribute is used by loss/risk function to return the loss value of the function at a given point together with the function gradient