Maude-help mailing list

["Francesoc Bongiovanni" <bongiovanni AT gmail.com>]

Hello,

I am stuck with some piece of Maude code and I am circling aroung it.

I basically coded the Pearson Correlation Coefficient function in Maude,
and came up with this bit of code :

  op sizeOf : List{Float} -> Float  .
    eq sizeOf(F1) = 1.0 .
    eq sizeOf(F1 V1) = (1.0 + sizeOf(V1)) .

    op sumAB : List{Float} List{Float} -> Float .
    eq sumAB(V1,V2)  = foldl plusF 0.0 (zipWith plusF V1 V2) .

    op sumA : List{Float} -> Float .
    eq sumA(V1) = foldl plusF 0.0 V1 .

    op sumOfSquare : List{Float} -> Float .
    eq sumOfSquare(V1) = foldl plusF 0.0 (map square V1) .

    op num : List{Float} List{Float} -> Float .
    eq num(V1,V2) =  ( ( sumAB(V1,V2) * sizeOf(V1) ) - ( sumA(V1) *
sumA(V2) ) )  .

I ll spare you the denum part.

When I try to load the module containing the op, in Full-Maude, it gives me
the following error :

Warning: Ambiguous parsing for (num(V1,V2))=(((sumAB(V1,V2)* sizeOf(V1))-
(sumA(V1)* sumA(V2))))
Error: no parse for eq num(V1,V2) = ((sumAB(V1,V2)* sizeOf(V1))-(sumA(V1)*
sumA(V2)))
Warning: Ambiguous parsing for (num(V1,V2))=(((sumAB(V1,V2)* sizeOf(V1))-
(sumA(V1)* sumA(V2))))
Error: no parse for eq num(V1,V2) = ((sumAB(V1,V2)* sizeOf(V1))-(sumA(V1)*
sumA(V2)))

When I change the `-` sign with a `+` sign the error goes away...I dont really
get it...how do I keep the minus sign without that error ?

Thanks for your insights !

- Francesco