Memory Allocator Reference
==========================
#include <fftw.h>
void *(*fftw_malloc_hook) (size_t n);
void (*fftw_free_hook) (void *p);
Whenever it has to allocate and release memory, FFTW ordinarily calls
`malloc' and `free'. If `malloc' fails, FFTW prints an error message
and exits. This behavior may be undesirable in some applications.
Also, special memory-handling functions may be necessary in certain
environments. Consequently, FFTW provides means by which you can install
your own memory allocator and take whatever error-correcting action you
find appropriate. The variables `fftw_malloc_hook' and
`fftw_free_hook' are pointers to functions, and they are normally
`NULL'. If you set those variables to point to other functions, then
FFTW will use your routines instead of `malloc' and `free'.
`fftw_malloc_hook' must point to a `malloc'-like function, and
`fftw_free_hook' must point to a `free'-like function.