From 5b2c8b77df14001b29b507b97a00c1194655bf5e Mon Sep 17 00:00:00 2001
From: Mark Borgerding <mark@borgerding.net>
Date: Sun, 7 Mar 2010 21:31:06 -0500
Subject: [PATCH] created FFT::fwd and FFT::inv with ReturnByValue

---
 unsupported/Eigen/FFT     | 63 +++++++++++++++++++++++++++++++++++++--
 unsupported/test/FFTW.cpp | 20 +++++++++++++
 2 files changed, 80 insertions(+), 3 deletions(-)

diff --git a/unsupported/Eigen/FFT b/unsupported/Eigen/FFT
index 3c4d85d3b..7108c20c5 100644
--- a/unsupported/Eigen/FFT
+++ b/unsupported/Eigen/FFT
@@ -110,12 +110,42 @@
 
 namespace Eigen {
 
-template <typename _Scalar,
-         typename _Impl=default_fft_impl<_Scalar> >
+
+ 
+// 
+template<typename T_SrcMat,typename T_FftIfc,bool T_ForwardTransform> 
+struct fft_result_proxy;
+
+template<typename T_SrcMat,typename T_FftIfc,bool T_ForwardTransform>
+struct ei_traits< fft_result_proxy<T_SrcMat,T_FftIfc,T_ForwardTransform> >
+{
+  typedef typename T_SrcMat::PlainObject ReturnType;
+};
+
+template<typename T_SrcMat,typename T_FftIfc,bool T_ForwardTransform> 
+struct fft_result_proxy
+ : public ReturnByValue<fft_result_proxy<T_SrcMat,T_FftIfc,T_ForwardTransform> >
+{
+  fft_result_proxy(const T_SrcMat& src,T_FftIfc & fft,int nfft) : m_src(src),m_ifc(fft), m_nfft(nfft) {}
+
+  template<typename T_DestMat> void evalTo(T_DestMat& dst) const;
+
+  int rows() const { return m_src.rows(); }
+  int cols() const { return m_src.cols(); }
+  protected:
+      const T_SrcMat & m_src;
+      T_FftIfc & m_ifc;
+      int m_nfft;
+};
+
+
+
+template <typename T_Scalar,
+         typename T_Impl=default_fft_impl<T_Scalar> >
 class FFT
 {
   public:
-    typedef _Impl impl_type;
+    typedef T_Impl impl_type;
     typedef typename impl_type::Scalar Scalar;
     typedef typename impl_type::Complex Complex;
 
@@ -204,6 +234,22 @@ class FFT
         fwd( &dst[0],&src[0],nfft );
       }
     }
+ 
+    template<typename InputDerived>
+    inline
+    fft_result_proxy< MatrixBase<InputDerived>, FFT<T_Scalar,T_Impl> ,true>
+    fwd( const MatrixBase<InputDerived> & src,int nfft=-1)
+    {
+      return  fft_result_proxy< MatrixBase<InputDerived> ,FFT<T_Scalar,T_Impl>,true>( src, *this,nfft );
+    }
+
+    template<typename InputDerived>
+    inline
+    fft_result_proxy< MatrixBase<InputDerived>, FFT<T_Scalar,T_Impl> ,false>
+    inv( const MatrixBase<InputDerived> & src,int nfft=-1)
+    {
+      return  fft_result_proxy< MatrixBase<InputDerived> ,FFT<T_Scalar,T_Impl>,false>( src, *this,nfft );
+    }
 
     inline
     void inv( Complex * dst, const Complex * src, int nfft)
@@ -335,6 +381,17 @@ class FFT
     impl_type m_impl;
     int m_flag;
 };
+
+template<typename T_SrcMat,typename T_FftIfc,bool T_ForwardTransform> 
+template<typename T_DestMat> inline 
+void fft_result_proxy<T_SrcMat,T_FftIfc,T_ForwardTransform>::evalTo(T_DestMat& dst) const
+{
+  if (T_ForwardTransform)
+    m_ifc.fwd( dst, m_src, m_nfft);
+  else
+    m_ifc.inv( dst, m_src, m_nfft);
+}
+
 }
 #endif
 /* vim: set filetype=cpp et sw=2 ts=2 ai: */
diff --git a/unsupported/test/FFTW.cpp b/unsupported/test/FFTW.cpp
index 838ddb238..66ffbae38 100644
--- a/unsupported/test/FFTW.cpp
+++ b/unsupported/test/FFTW.cpp
@@ -225,8 +225,28 @@ void test_complex2d()
 }
 */
 
+
+template <typename T,int nrows,int ncols>
+void test_return_by_value()
+{
+    Matrix<complex<T>,nrows,ncols> in;
+    Matrix<complex<T>,nrows,ncols> in1;
+    in.Random();
+    Matrix<complex<T>,nrows,ncols> out1;
+    Matrix<complex<T>,nrows,ncols> out2;
+    FFT<T> fft;
+    fft.fwd(out1,in);
+    out2 = fft.fwd(in);
+    VERIFY( (out1-out2).norm() < test_precision<T>() );
+    in1 = fft.inv(out1);
+    VERIFY( (in1-in).norm() < test_precision<T>() );
+}
+
 void test_FFTW()
 {
+    test_return_by_value<float,1,32>();
+    test_return_by_value<double,1,32>();
+    //test_return_by_value<long double,1,32>();
   //CALL_SUBTEST( ( test_complex2d<float,4,8> () ) ); CALL_SUBTEST( ( test_complex2d<double,4,8> () ) );
   //CALL_SUBTEST( ( test_complex2d<long double,4,8> () ) );
   CALL_SUBTEST( test_complex<float>(32) ); CALL_SUBTEST( test_complex<double>(32) ); CALL_SUBTEST( test_complex<long double>(32) );