python - Cython memoryviews error: Invalid index for memoryview specified -

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i'm trying implement standard quicksort in cython using memoryviews. here code:

def quicksort_cython(double[:] l):     _quicksort(l, 0, len(l) - 1)   cdef void _quicksort(double[:] l, double start, double stop):     cdef double pivot, left, right, tmp     if stop - start > 0:         pivot = l[start]         left = start         right = stop         while left <= right:             while l[left] < pivot:                 left += 1             while l[right] > pivot:                 right -= 1             if left <= right:                 tmp = l[left]                 l[left] = l[right]                 l[right] = tmp                 left += 1                 right -= 1         _quicksort(l, start, right)         _quicksort(l, left, stop)

however, during compilation standard setup.py file , python setup.py build_ext --inplace command multiple errors regarding memoryview access:

error compiling cython file: ------------------------------------------------------------ ...   cdef void _quicksort(double[:] l, double start, double stop):     cdef double pivot, left, right, tmp     if stop - start > 0:         pivot = l[start]                       ^ ------------------------------------------------------------  quicksort_cython_opt3.pyx:9:23: invalid index memoryview specified

can tell me doing wrong? performance improving tips appreciated i'm new cython.. thanks!

typically doubles can't indices (should ints). assume that's problem...although i'm admittedly not familiar cython memoryviews.


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