diff --git a/cmake b/cmake
deleted file mode 160000
index 05b6961..0000000
--- a/cmake
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 05b696123f379245483f7b7a1ff4abeb6f490667
diff --git a/cmake/FindFFTW.cmake b/cmake/FindFFTW.cmake
new file mode 100644
index 0000000..8b7ef3c
--- /dev/null
+++ b/cmake/FindFFTW.cmake
@@ -0,0 +1,339 @@
+# - Find the FFTW library
+#
+# Original version of this file:
+#   Copyright (c) 2015, Wenzel Jakob
+#   https://github.com/wjakob/layerlab/blob/master/cmake/FindFFTW.cmake, commit 4d58bfdc28891b4f9373dfe46239dda5a0b561c6
+# Modifications:
+#   Copyright (c) 2017, Patrick Bos
+#
+# Usage:
+#   find_package(FFTW [REQUIRED] [QUIET] [COMPONENTS component1 ... componentX] )
+#
+# It sets the following variables:
+#   FFTW_FOUND                  ... true if fftw is found on the system
+#   FFTW_[component]_LIB_FOUND  ... true if the component is found on the system (see components below)
+#   FFTW_LIBRARIES              ... full paths to all found fftw libraries
+#   FFTW_[component]_LIB        ... full path to one of the components (see below)
+#   FFTW_INCLUDE_DIRS           ... fftw include directory paths
+#
+# The following variables will be checked by the function
+#   FFTW_USE_STATIC_LIBS        ... if true, only static libraries are found, otherwise both static and shared.
+#   FFTW_ROOT                   ... if set, the libraries are exclusively searched
+#                                   under this path
+#
+# This package supports the following components:
+#   FLOAT_LIB
+#   DOUBLE_LIB
+#   LONGDOUBLE_LIB
+#   FLOAT_THREADS_LIB
+#   DOUBLE_THREADS_LIB
+#   LONGDOUBLE_THREADS_LIB
+#   FLOAT_OPENMP_LIB
+#   DOUBLE_OPENMP_LIB
+#   LONGDOUBLE_OPENMP_LIB
+#
+
+# TODO (maybe): extend with ExternalProject download + build option
+# TODO: put on conda-forge
+
+
+if( NOT FFTW_ROOT AND DEFINED ENV{FFTWDIR} )
+  set( FFTW_ROOT $ENV{FFTWDIR} )
+endif()
+
+# Check if we can use PkgConfig
+find_package(PkgConfig)
+
+#Determine from PKG
+if( PKG_CONFIG_FOUND AND NOT FFTW_ROOT )
+  pkg_check_modules( PKG_FFTW QUIET "fftw3" )
+endif()
+
+#Check whether to search static or dynamic libs
+set( CMAKE_FIND_LIBRARY_SUFFIXES_SAV ${CMAKE_FIND_LIBRARY_SUFFIXES} )
+
+if( ${FFTW_USE_STATIC_LIBS} )
+  set( CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_STATIC_LIBRARY_SUFFIX} )
+else()
+  set( CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES_SAV} )
+endif()
+
+if( FFTW_ROOT )
+  # find libs
+
+  find_library(
+    FFTW_DOUBLE_LIB
+    NAMES "fftw3" libfftw3-3
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "lib" "lib64"
+    NO_DEFAULT_PATH
+  )
+
+  find_library(
+    FFTW_DOUBLE_THREADS_LIB
+    NAMES "fftw3_threads"
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "lib" "lib64"
+    NO_DEFAULT_PATH
+  )
+
+  find_library(
+          FFTW_DOUBLE_OPENMP_LIB
+          NAMES "fftw3_omp"
+          PATHS ${FFTW_ROOT}
+          PATH_SUFFIXES "lib" "lib64"
+          NO_DEFAULT_PATH
+  )
+
+  find_library(
+    FFTW_FLOAT_LIB
+    NAMES "fftw3f" libfftw3f-3
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "lib" "lib64"
+    NO_DEFAULT_PATH
+  )
+
+  find_library(
+    FFTW_FLOAT_THREADS_LIB
+    NAMES "fftw3f_threads"
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "lib" "lib64"
+    NO_DEFAULT_PATH
+  )
+
+  find_library(
+          FFTW_FLOAT_OPENMP_LIB
+          NAMES "fftw3f_omp"
+          PATHS ${FFTW_ROOT}
+          PATH_SUFFIXES "lib" "lib64"
+          NO_DEFAULT_PATH
+  )
+
+  find_library(
+    FFTW_LONGDOUBLE_LIB
+    NAMES "fftw3l" libfftw3l-3
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "lib" "lib64"
+    NO_DEFAULT_PATH
+  )
+
+  find_library(
+    FFTW_LONGDOUBLE_THREADS_LIB
+    NAMES "fftw3l_threads"
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "lib" "lib64"
+    NO_DEFAULT_PATH
+  )
+
+  find_library(
+          FFTW_LONGDOUBLE_OPENMP_LIB
+          NAMES "fftw3l_omp"
+          PATHS ${FFTW_ROOT}
+          PATH_SUFFIXES "lib" "lib64"
+          NO_DEFAULT_PATH
+  )
+
+  #find includes
+  find_path(FFTW_INCLUDE_DIRS
+    NAMES "fftw3.h"
+    PATHS ${FFTW_ROOT}
+    PATH_SUFFIXES "include"
+    NO_DEFAULT_PATH
+  )
+
+else()
+
+  find_library(
+    FFTW_DOUBLE_LIB
+    NAMES "fftw3"
+    PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+    FFTW_DOUBLE_THREADS_LIB
+    NAMES "fftw3_threads"
+    PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+          FFTW_DOUBLE_OPENMP_LIB
+          NAMES "fftw3_omp"
+          PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+    FFTW_FLOAT_LIB
+    NAMES "fftw3f"
+    PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+    FFTW_FLOAT_THREADS_LIB
+    NAMES "fftw3f_threads"
+    PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+          FFTW_FLOAT_OPENMP_LIB
+          NAMES "fftw3f_omp"
+          PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+    FFTW_LONGDOUBLE_LIB
+    NAMES "fftw3l"
+    PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(
+    FFTW_LONGDOUBLE_THREADS_LIB
+    NAMES "fftw3l_threads"
+    PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_library(FFTW_LONGDOUBLE_OPENMP_LIB
+          NAMES "fftw3l_omp"
+          PATHS ${PKG_FFTW_LIBRARY_DIRS} ${LIB_INSTALL_DIR}
+  )
+
+  find_path(FFTW_INCLUDE_DIRS
+    NAMES "fftw3.h"
+    PATHS ${PKG_FFTW_INCLUDE_DIRS} ${INCLUDE_INSTALL_DIR}
+  )
+
+endif( FFTW_ROOT )
+
+#--------------------------------------- components
+
+if (FFTW_DOUBLE_LIB)
+  set(FFTW_DOUBLE_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_DOUBLE_LIB})
+  add_library(FFTW::Double INTERFACE IMPORTED)
+  set_target_properties(FFTW::Double
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_DOUBLE_LIB}"
+  )
+else()
+  set(FFTW_DOUBLE_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_FLOAT_LIB)
+  set(FFTW_FLOAT_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_FLOAT_LIB})
+  add_library(FFTW::Float INTERFACE IMPORTED)
+  set_target_properties(FFTW::Float
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_FLOAT_LIB}"
+  )
+else()
+  set(FFTW_FLOAT_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_LONGDOUBLE_LIB)
+  set(FFTW_LONGDOUBLE_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_LONGDOUBLE_LIB})
+  add_library(FFTW::LongDouble INTERFACE IMPORTED)
+  set_target_properties(FFTW::LongDouble
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_LONGDOUBLE_LIB}"
+  )
+else()
+  set(FFTW_LONGDOUBLE_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_DOUBLE_THREADS_LIB)
+  set(FFTW_DOUBLE_THREADS_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_DOUBLE_THREADS_LIB})
+  add_library(FFTW::DoubleThreads INTERFACE IMPORTED)
+  set_target_properties(FFTW::DoubleThreads
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_DOUBLETHREADS_LIB}"
+  )
+else()
+  set(FFTW_DOUBLE_THREADS_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_FLOAT_THREADS_LIB)
+  set(FFTW_FLOAT_THREADS_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_FLOAT_THREADS_LIB})
+  add_library(FFTW::FloatThreads INTERFACE IMPORTED)
+  set_target_properties(FFTW::FloatThreads
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_FLOAT_THREADS_LIB}"
+  )
+else()
+  set(FFTW_FLOAT_THREADS_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_LONGDOUBLE_THREADS_LIB)
+  set(FFTW_LONGDOUBLE_THREADS_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_LONGDOUBLE_THREADS_LIB})
+  add_library(FFTW::LongDoubleThreads INTERFACE IMPORTED)
+  set_target_properties(FFTW::LongDoubleThreads
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_LONGDOUBLE_THREADS_LIB}"
+  )
+else()
+  set(FFTW_LONGDOUBLE_THREADS_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_DOUBLE_OPENMP_LIB)
+  set(FFTW_DOUBLE_OPENMP_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_DOUBLE_OPENMP_LIB})
+  add_library(FFTW::DoubleOpenMP INTERFACE IMPORTED)
+  set_target_properties(FFTW::DoubleOpenMP
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_DOUBLE_OPENMP_LIB}"
+  )
+else()
+  set(FFTW_DOUBLE_OPENMP_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_FLOAT_OPENMP_LIB)
+  set(FFTW_FLOAT_OPENMP_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_FLOAT_OPENMP_LIB})
+  add_library(FFTW::FloatOpenMP INTERFACE IMPORTED)
+  set_target_properties(FFTW::FloatOpenMP
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_FLOAT_OPENMP_LIB}"
+  )
+else()
+  set(FFTW_FLOAT_OPENMP_LIB_FOUND FALSE)
+endif()
+
+if (FFTW_LONGDOUBLE_OPENMP_LIB)
+  set(FFTW_LONGDOUBLE_OPENMP_LIB_FOUND TRUE)
+  set(FFTW_LIBRARIES ${FFTW_LIBRARIES} ${FFTW_LONGDOUBLE_OPENMP_LIB})
+  add_library(FFTW::LongDoubleOpenMP INTERFACE IMPORTED)
+  set_target_properties(FFTW::LongDoubleOpenMP
+    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${FFTW_INCLUDE_DIRS}"
+               INTERFACE_LINK_LIBRARIES "${FFTW_LONGDOUBLE_OPENMP_LIB}"
+  )
+else()
+  set(FFTW_LONGDOUBLE_OPENMP_LIB_FOUND FALSE)
+endif()
+
+#--------------------------------------- end components
+
+set( CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES_SAV} )
+
+include(FindPackageHandleStandardArgs)
+
+find_package_handle_standard_args(FFTW
+        REQUIRED_VARS FFTW_INCLUDE_DIRS
+        HANDLE_COMPONENTS
+        )
+
+mark_as_advanced(
+        FFTW_INCLUDE_DIRS
+        FFTW_LIBRARIES
+        FFTW_FLOAT_LIB
+        FFTW_DOUBLE_LIB
+        FFTW_LONGDOUBLE_LIB
+        FFTW_FLOAT_THREADS_LIB
+        FFTW_DOUBLE_THREADS_LIB
+        FFTW_LONGDOUBLE_THREADS_LIB
+        FFTW_FLOAT_OPENMP_LIB
+        FFTW_DOUBLE_OPENMP_LIB
+        FFTW_LONGDOUBLE_OPENMP_LIB
+        )
diff --git a/cmake/LICENSE b/cmake/LICENSE
new file mode 100644
index 0000000..6e15259
--- /dev/null
+++ b/cmake/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2015, Wenzel Jakob; 2017, Patrick Bos
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of the copyright holder nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/cmake/README.md b/cmake/README.md
new file mode 100644
index 0000000..1283ded
--- /dev/null
+++ b/cmake/README.md
@@ -0,0 +1,104 @@
+CMake module for finding FFTW 3 using find_package
+
+# Usage
+
+Once added to your project, this module allows you to find FFTW libraries and headers using the CMake `find_package` command:
+
+```cmake
+find_package(FFTW [REQUIRED] [QUIET] [COMPONENTS component1 ... componentX] )
+```
+
+This module sets the following variables:
+- `FFTW_FOUND`                  ... true if fftw is found on the system
+- `FFTW_[component]_LIB_FOUND`  ... true if the component is found on the system (see components below)
+- `FFTW_LIBRARIES`              ... full paths to all found fftw libraries
+- `FFTW_[component]_LIB`        ... full path to one of the components (see below)
+- `FFTW_INCLUDE_DIRS`           ... fftw include directory paths
+
+The following variables will be checked by the module:
+- `FFTW_USE_STATIC_LIBS`        ... if true, only static libraries are found, otherwise both static and shared.
+- `FFTW_ROOT`                   ... if set, the libraries are exclusively searched under this path.
+
+This package supports the following components:
+- `FLOAT_LIB`
+- `DOUBLE_LIB`
+- `LONGDOUBLE_LIB`
+- `FLOAT_THREADS_LIB`
+- `DOUBLE_THREADS_LIB`
+- `LONGDOUBLE_THREADS_LIB`
+- `FLOAT_OPENMP_LIB`
+- `DOUBLE_OPENMP_LIB`
+- `LONGDOUBLE_OPENMP_LIB`
+
+and the following linking targets
+
+- `FFTW::Float`
+- `FFTW::Double`
+- `FFTW::LongDouble`
+- `FFTW::FloatThreads`
+- `FFTW::DoubleThreads`
+- `FFTW::LongDoubleThreads`
+- `FFTW::FloatOpenMP`
+- `FFTW::DoubleOpenMP`
+- `FFTW::LongDoubleOpenMP`
+
+# Adding to your project
+
+## Automatic download from CMake project
+
+Copy the following into the `CMakeLists.txt` file of the project you want to use FindFFTW in:
+```cmake
+configure_file(downloadFindFFTW.cmake.in findFFTW-download/CMakeLists.txt)
+execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
+        RESULT_VARIABLE result
+        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/findFFTW-download )
+if(result)
+    message(FATAL_ERROR "CMake step for findFFTW failed: ${result}")
+    else()
+    message("CMake step for findFFTW completed (${result}).")
+endif()
+execute_process(COMMAND ${CMAKE_COMMAND} --build .
+        RESULT_VARIABLE result
+        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/findFFTW-download )
+if(result)
+    message(FATAL_ERROR "Build step for findFFTW failed: ${result}")
+endif()
+
+set(findFFTW_DIR ${CMAKE_CURRENT_BINARY_DIR}/findFFTW-src)
+
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${findFFTW_DIR}")
+```
+
+And add a file called `downloadFindFFTW.cmake.in` to your project containing the following:
+```cmake
+cmake_minimum_required(VERSION 2.8.2)
+
+project(findFFTW-download NONE)
+
+include(ExternalProject)
+
+ExternalProject_Add(findFFTW_download
+    GIT_REPOSITORY    "https://github.com/egpbos/findfftw.git"
+    CONFIGURE_COMMAND ""
+    BUILD_COMMAND     ""
+    INSTALL_COMMAND   ""
+    TEST_COMMAND      ""
+    SOURCE_DIR        "${CMAKE_CURRENT_BINARY_DIR}/findFFTW-src"
+    BINARY_DIR        ""
+    INSTALL_DIR       ""
+)
+```
+
+After this, `find_package(FFTW)` can be used in the `CMakeLists.txt` file.
+
+## Manual
+
+Clone the repository into directory `PREFIX/findFFTW`:
+```sh
+git clone https://github.com/egpbos/findfftw.git PREFIX/findFFTW
+```
+
+Then add the following to your `CMakeLists.txt` to allow CMake to find the module:
+```cmake
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "PREFIX/findFFTW")
+```