Jupyter notebook SyntaxError: invalid syntax from libc.math cimport sqrt

Question

I tried this at jupyter notebook

%load_ext Cython

I was able to install cython successfully but I couldn't use cimport

%%cython

from libc.math cimport sqrt
import numpy as np

def filt_conv3(double complex[:,:] filterInput, Py_ssize_t sample_per_symbol, double[:] h, int flag, Py_ssize_t num_of_taps):
    cdef Py_ssize_t input_batch_size = filterInput.shape[0]
    cdef Py_ssize_t input_length = filterInput.shape[1]

    cdef Py_ssize_t num_of_output = num_of_taps + (input_length-1) * sample_per_symbol  
    cdef double complex[:,:] output = np.zeros((input_batch_size, num_of_output), dtype=np.complex)  
    cdef double complex[:,:] FiltSig = np.zeros((input_batch_size, num_of_output), dtype=np.complex)  

    

But it returned me the following error:

Cell In[12], line 4
    from libc.math cimport sqrt
                   ^
SyntaxError: invalid syntax

What is the cause of this syntax error? What should I do?

I replaced cimport with import

%%cython

from libc.math import sqrt
import numpy as np

I got another error

def filt_conv3(double complex[:,:] filterInput, Py_ssize_t sample_per_symbol, double[:] h, int flag, Py_ssize_t num_of_taps):
                          ^
SyntaxError: invalid syntax`your text`

And also this code got error

import numpy as np
cimport cython
from libc.math cimport sqrt

cimport cython
        ^
SyntaxError: invalid syntax

Answer 1

Well, I ran your original code in jupyter and got no error. But I got the same error if I put a annotation line #test befere %%cython line. You can try to make sure the %%cython line is at the very top of your code block.