empty hmatrix-base

1 files changed, 47 insertions, 0 deletions

diff --git a/packages/hmatrix/src/Numeric/GSL/Fourier.hs b/packages/hmatrix/src/Numeric/GSL/Fourier.hs
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+++ b/packages/hmatrix/src/Numeric/GSL/Fourier.hs
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+{-# LANGUAGE ForeignFunctionInterface #-}
+-----------------------------------------------------------------------------
+{- |
+Module      : Numeric.GSL.Fourier
+Copyright   :  (c) Alberto Ruiz 2006
+License     :  GPL-style
+
+Maintainer  :  Alberto Ruiz (aruiz at um dot es)
+Stability   :  provisional
+Portability :  uses ffi
+
+Fourier Transform.
+
+<http://www.gnu.org/software/gsl/manual/html_node/Fast-Fourier-Transforms.html#Fast-Fourier-Transforms>
+
+-}
+-----------------------------------------------------------------------------
+module Numeric.GSL.Fourier (
+    fft,
+    ifft
+) where
+
+import Data.Packed.Internal
+import Data.Complex
+import Foreign.C.Types
+import System.IO.Unsafe (unsafePerformIO)
+
+genfft code v = unsafePerformIO $ do
+    r <- createVector (dim v)
+    app2 (c_fft code) vec v vec r "fft"
+    return r
+
+foreign import ccall unsafe "gsl-aux.h fft" c_fft ::  CInt -> TCVCV
+
+
+{- | Fast 1D Fourier transform of a 'Vector' @(@'Complex' 'Double'@)@ using /gsl_fft_complex_forward/. It uses the same scaling conventions as GNU Octave.
+
+>>> fft (fromList [1,2,3,4])
+fromList [10.0 :+ 0.0,(-2.0) :+ 2.0,(-2.0) :+ 0.0,(-2.0) :+ (-2.0)]
+
+-}
+fft :: Vector (Complex Double) -> Vector (Complex Double)
+fft = genfft 0
+
+-- | The inverse of 'fft', using /gsl_fft_complex_inverse/.
+ifft :: Vector (Complex Double) -> Vector (Complex Double)
+ifft = genfft 1