Chris@42: Previous: Precision, Up: Data Types and Files [Contents][Index]
Chris@42:void *fftw_malloc(size_t n); Chris@42: void fftw_free(void *p); Chris@42:
These are functions that behave identically to malloc and
Chris@42: free, except that they guarantee that the returned pointer obeys
Chris@42: any special alignment restrictions imposed by any algorithm in FFTW
Chris@42: (e.g. for SIMD acceleration). See SIMD alignment and fftw_malloc.
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Data allocated by fftw_malloc must be deallocated by
Chris@42: fftw_free and not by the ordinary free.
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These routines simply call through to your operating system’s
Chris@42: malloc or, if necessary, its aligned equivalent
Chris@42: (e.g. memalign), so you normally need not worry about any
Chris@42: significant time or space overhead. You are not required to use
Chris@42: them to allocate your data, but we strongly recommend it.
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Note: in C++, just as with ordinary malloc, you must typecast
Chris@42: the output of fftw_malloc to whatever pointer type you are
Chris@42: allocating.
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We also provide the following two convenience functions to allocate
Chris@42: real and complex arrays with n elements, which are equivalent
Chris@42: to (double *) fftw_malloc(sizeof(double) * n) and
Chris@42: (fftw_complex *) fftw_malloc(sizeof(fftw_complex) * n),
Chris@42: respectively:
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double *fftw_alloc_real(size_t n); Chris@42: fftw_complex *fftw_alloc_complex(size_t n); Chris@42:
The equivalent functions in other precisions allocate arrays of n
Chris@42: elements in that precision. e.g. fftwf_alloc_real(n) is
Chris@42: equivalent to (float *) fftwf_malloc(sizeof(float) * n).
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