Our purpose is to introduce the W-composition, W-minimalization and W-primitive recursion operations as operations between W-valued functions, where W denotes the ordered semiring ([0,1],+,≤). We prove that: 1) the set of W-calculable functions is closed under the W-composition and W-primitice recursion operations, and 2) the set of the partially W-calculable functions is closed under the W-minimalization operation.