def _is_safe_size(n):
 n = int(n)
 if (n == 0):
  return True
 for c in (3, 5):
  while ((n % c) == 0):
   n //= c
 return (not (n & (n - 1)))

def _is_safe_size ( n ) : n = int ( n ) if ( n == 0 ) : return True for c in ( 3 , 5 ) : while ( ( n % c ) == 0 ) : n //= c return ( not ( n & ( n - 1 ) ) )
is the size of fft such that fftpack can handle it in single precision with sufficient accuracy? composite numbers of 2 .