Define inverse for unary plus and minus

Author: oschulz

src/inverse.jl

@@ -85,6 +85,9 @@ inverse(::typeof(inv)) = inv
 inverse(::typeof(adjoint)) = adjoint
 inverse(::typeof(transpose)) = transpose
 
+inverse(::typeof(+)) = +
+inverse(::typeof(-)) = -
+
 inverse(::typeof(exp)) = log
 inverse(::typeof(log)) = exp
 

test/test_inverse.jl

@@ -29,7 +29,7 @@ InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
     InverseFunctions.test_inverse(inverse, log, compare = ===)
 
     x = rand()
-    for f in (foo, inv_foo, exp, log, exp2, log2, exp10, log10, expm1, log1p, sqrt)
+    for f in (foo, inv_foo, +, -, exp, log, exp2, log2, exp10, log10, expm1, log1p, sqrt)
         InverseFunctions.test_inverse(f, x)
     end