gnu: Add r-acopula.

* gnu/packages/cran.scm (r-acopula): New variable.

gnu/packages/cran.scm

@@ -17347,3 +17347,29 @@ (define-public r-acnr
 regions.  These regions were identified manually by the authors of the package
 and may be used to generate realistic data sets with known truth.")
     (license license:lgpl2.1+)))
+
+(define-public r-acopula
+  (package
+    (name "r-acopula")
+    (version "0.9.3")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (cran-uri "acopula" version))
+       (sha256
+        (base32
+         "0vvbbw8pfs9jwfz5c57lw48pr0qj661r0ys007q6zf9jmlrhx1ln"))))
+    (properties `((upstream-name . "acopula")))
+    (build-system r-build-system)
+    (home-page "https://cran.r-project.org/web/packages/acopula/")
+    (synopsis "Modelling dependence with multivariate Archimax copulas")
+    (description
+     "Archimax copulas are a mixture of Archimedean and EV copulas.  This
+package provides definitions of several parametric families of generator and
+dependence function, computes CDF and PDF, estimates parameters, tests for
+goodness of fit, generates random sample and checks copula properties for
+custom constructs.  In the 2-dimensional case explicit formulas for density
+are used, contrary to higher dimensions when all derivatives are linearly
+approximated.  Several non-archimax families (normal, FGM, Plackett) are
+provided as well.")
+    (license license:gpl2)))