FFT module revamp.

- Added several new functionnalities to the FFT module by changing the dependency from FFTPACK to POCKETFTT.
	- new optionnal parameters for the API (nthreads, norm, ...)
	- new functions for cosine and sine transforms (dct, dst, ...)
- Switched from dune 2.0 to dune 3.16 (this was required as I ran throught issues with linking while using 2.0)

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "src/owl/fftpack/pocketfft"]
+	path = src/owl/fftpack/pocketfft
+	url = https://github.com/mreineck/pocketfft

dune-project

@@ -1,3 +1,3 @@
-(lang dune 2.0)
+(lang dune 3.16)
 
 (name owl)

examples/dune

@@ -1,5 +1,5 @@
 (executables
- (names 
+ (names
   backprop
   checkpoint
   cifar10_vgg
@@ -25,6 +25,15 @@
   squeezenet
   test_log
   tfidf
-  vgg16
- )
- (libraries owl))
+  vgg16)
+ (libraries owl)
+ (flags ; in order to make the examples compile correctly even with the warnings.
+  (:standard
+   -warn-error
+   -unused-value-declaration
+   -warn-error
+   -unused-var-strict
+   -warn-error
+   -unused-var
+   -warn-error
+   -unused-field)))

src/base/core/owl_graph.ml

@@ -13,7 +13,7 @@ type 'a node =
     mutable next : 'a node array
   ; (* children of the node *)
     mutable attr : 'a (* indicate the validity *)
-  }
+  } [@@warning "-69"]
 
 type order =
   | BFS

src/owl/dune

@@ -32,6 +32,8 @@
 
 (copy_files# fftpack/*)
 
+(copy_files# fftpack/pocketfft/*.h)
+
 (copy_files# misc/*)
 
 (copy_files# nlp/*)
@@ -42,6 +44,15 @@
  (name owl)
  (public_name owl)
  (wrapped false)
+ (foreign_stubs
+  (language cxx)
+  (names
+   ;; FFTPACK
+   owl_fftpack_float32
+   owl_fftpack_float64)
+  (flags
+   :standard
+   (:include c_flags.sexp)))
  (foreign_stubs
   (language c)
   (names
@@ -65,9 +76,6 @@
    owl_ndarray_utils_stub
    owl_slicing_basic_stub
    owl_slicing_fancy_stub
-   ;; FFTPACK
-   owl_fftpack_float32
-   owl_fftpack_float64
    ;; stats
    SFMT
    owl_stats_dist_beta
@@ -202,7 +210,8 @@
    (:include c_flags.sexp)))
  (c_library_flags
   :standard
-  (:include c_library_flags.sexp))
+  (:include c_library_flags.sexp)
+  -lstdc++)
  (flags
   :standard
   (:include ocaml_flags.sexp))