Feature/negation (#28)

Adds negation operator

Author: mathias-nillion

nada_algebra/array.py

@@ -182,6 +182,17 @@ def __imul__(self, other: Any) -> "NadaArray":
         """
         return self.mul(other)
 
+    def __neg__(self) -> "NadaArray":
+        """
+        Performs negation operation.
+
+        Returns:
+            NadaArray: Negated NadaArray.
+        """
+        if self.is_rational:
+            return self.apply(lambda x: x * rational(-1))
+        return self.apply(lambda x: x * Integer(-1))
+
     def __pow__(self, other: int) -> "NadaArray":
         """
         Raises NadaArray to a power.

tests/nada-tests/src/rational_array.py

@@ -19,6 +19,8 @@ def nada_main():
     out_6 = a * c
     out_7 = a / c
 
+    out_8 = -a
+
     return (
         out_0.output(parties[1], "out_0")
         + out_1.output(parties[1], "out_1")
@@ -28,4 +30,5 @@ def nada_main():
         + out_5.output(parties[1], "out_5")
         + out_6.output(parties[1], "out_6")
         + out_7.output(parties[1], "out_7")
+        + out_8.output(parties[1], "out_8")
     )

tests/nada-tests/tests/rational_array.yaml

@@ -64,3 +64,9 @@ expected_outputs:
     SecretInteger: "65536"
   out_7_2:
     SecretInteger: "131072"
+  out_8_0:
+    SecretInteger: "0"
+  out_8_1:
+    SecretInteger: "-65536"
+  out_8_2:
+    SecretInteger: "-131072"