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[Vlad Avram <vladz.avram AT gmail.com>]

Hi,

I'm trying to implement a module for complex numbers in Maude and here's what I got for now:

fmod COMPLEX is

  protecting FLOAT .

  sort Complex .

op complex : Float Float -> Complex .

op realpart : Complex -> Float .

op imagpart : Complex -> Float .

op _+_ : Complex Complex -> Complex [assoc comm] .

op _-_ : Complex Complex -> Complex .

op _*_ : Complex Complex -> Complex .

op _/_ : Complex Complex -> Complex .

vars X Y : Complex .

vars R1 R2 : Float .

eq realpart(complex(R1,R2)) = R1 .

eq realpart(X + Y) = realpart(X) + realpart(Y) .

eq realpart(X - Y) = realpart(X) - realpart(Y) .

eq realpart(X * Y) = realpart(X) * realpart(Y) - imagpart(X) * imagpart(Y) .

ceq realpart(X / Y) = (realpart(X) * realpart(Y) + imagpart(X) * imagpart(Y)) / (realpart(Y) ^ 2.0 + imagpart(Y) ^ 2.0) if realpart(Y) =/= 0.0 and imagpart(Y) =/= 0.0 .  

eq imagpart(complex(R1,R2)) = R2 .

eq imagpart(X + Y) = imagpart(X) + imagpart(Y) .

eq imagpart(X - Y) = imagpart(X) - imagpart(Y) .

eq imagpart(X * Y) = imagpart(X) * realpart(Y) + realpart(X) * imagpart(Y) .

ceq imagpart(X / Y) = (imagpart(X) * realpart(Y) - realpart(X) * imagpart(Y)) / (realpart(Y) ^ 2.0 + imagpart(Y) ^ 2.0) if realpart(Y) =/= 0.0 and imagpart(Y) =/= 0.0 .

eq X + Y = complex(realpart(X + Y),imagpart(X + Y)) .

eq X - Y = complex(realpart(X - Y),imagpart(X - Y)) .

eq X * Y = complex(realpart(X * Y),imagpart(X * Y)) .

eq X / Y = complex(realpart(X / Y),imagpart(X / Y)) .

endfm

The parsing works but when I try something like "red complex(2.0,1.0) + complex(3.0,1.0)", Maude crashes. Can I please get an answer of what I'm doing wrong?

Thanks!