How is math-round different from other Calc functions?

[Daniele Nicolodi]

Hello,

it is possible to invoke Calc functions on quantities with units:

(calc-eval "sqrt(4.0 g)")
"2. sqrt(g)"

However, it this does not work for round():

(calc-eval "round(4.0 g)")
"round(4. g)"

Not knowing what is going on, I decided to build my own Calc function 
that does what is required:

(defmath uround (x)
  (* (round (remove-units x)) (extract-units x)))

However, this somehow does not work:

(calc-eval "uround(2.345 g)")
"uround(2.345 g)"

but it does if I replace round() with any other function:

(defmath uplus (x)
  (* (1+ (remove-units x)) (calc-eval "kg" 'raw)))

(calc-eval "uplus(2.345 g)")
"3.345 g"

Why is it so? How do I work around this?

Thank you.

Cheers,
Dan