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fftw3: Memory Allocation

 
 4.1.3 Memory Allocation
 -----------------------
 
      void *fftw_malloc(size_t n);
      void fftw_free(void *p);
 
    These are functions that behave identically to 'malloc' and 'free',
 except that they guarantee that the returned pointer obeys any special
 alignment restrictions imposed by any algorithm in FFTW (e.g.  for SIMD
 acceleration).  SIMD alignment and fftw_malloc.
 
    Data allocated by 'fftw_malloc' _must_ be deallocated by 'fftw_free'
 and not by the ordinary 'free'.
 
    These routines simply call through to your operating system's
 'malloc' or, if necessary, its aligned equivalent (e.g.  'memalign'), so
 you normally need not worry about any significant time or space
 overhead.  You are _not required_ to use them to allocate your data, but
 we strongly recommend it.
 
    Note: in C++, just as with ordinary 'malloc', you must typecast the
 output of 'fftw_malloc' to whatever pointer type you are allocating.
 
    We also provide the following two convenience functions to allocate
 real and complex arrays with 'n' elements, which are equivalent to
 '(double *) fftw_malloc(sizeof(double) * n)' and '(fftw_complex *)
 fftw_malloc(sizeof(fftw_complex) * n)', respectively:
 
      double *fftw_alloc_real(size_t n);
      fftw_complex *fftw_alloc_complex(size_t n);
 
    The equivalent functions in other precisions allocate arrays of 'n'
 elements in that precision.  e.g.  'fftwf_alloc_real(n)' is equivalent
 to '(float *) fftwf_malloc(sizeof(float) * n)'.
 

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