Add inverse

Author: DominiqueMakowski

ext/LogExpFunctionsInverseFunctionsExt.jl

@@ -22,4 +22,7 @@ InverseFunctions.inverse(::typeof(logitexp)) = loglogistic
 InverseFunctions.inverse(::typeof(log1mlogistic)) = logit1mexp
 InverseFunctions.inverse(::typeof(logit1mexp)) = log1mlogistic
 
+InverseFunctions.inverse(::typeof(softplus)) = invsofplus
+InverseFunctions.inverse(::typeof(invsofplus)) = softplus
+
 end # module

test/inverse.jl

@@ -17,4 +17,7 @@
 
     InverseFunctions.test_inverse(log1mlogistic, randexp())
     InverseFunctions.test_inverse(logit1mexp, -randexp())
+
+    InverseFunctions.test_inverse(softplus, randn())
+    InverseFunctions.test_inverse(invsoftplus, randexp())
 end