cannam@167: Previous: Precision, Up: Data Types and Files [Contents][Index]
cannam@167:void *fftw_malloc(size_t n); cannam@167: void fftw_free(void *p); cannam@167:
These are functions that behave identically to malloc and
cannam@167: free, except that they guarantee that the returned pointer obeys
cannam@167: any special alignment restrictions imposed by any algorithm in FFTW
cannam@167: (e.g. for SIMD acceleration). See SIMD alignment and fftw_malloc.
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Data allocated by fftw_malloc must be deallocated by
cannam@167: fftw_free and not by the ordinary free.
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These routines simply call through to your operating system’s
cannam@167: malloc or, if necessary, its aligned equivalent
cannam@167: (e.g. memalign), so you normally need not worry about any
cannam@167: significant time or space overhead. You are not required to use
cannam@167: 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
cannam@167: the output of fftw_malloc to whatever pointer type you are
cannam@167: allocating.
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We also provide the following two convenience functions to allocate
cannam@167: real and complex arrays with n elements, which are equivalent
cannam@167: to (double *) fftw_malloc(sizeof(double) * n) and
cannam@167: (fftw_complex *) fftw_malloc(sizeof(fftw_complex) * n),
cannam@167: respectively:
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double *fftw_alloc_real(size_t n); cannam@167: fftw_complex *fftw_alloc_complex(size_t n); cannam@167:
The equivalent functions in other precisions allocate arrays of n
cannam@167: elements in that precision. e.g. fftwf_alloc_real(n) is
cannam@167: equivalent to (float *) fftwf_malloc(sizeof(float) * n).
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